Luke Freeland from the blog https://metillium.com/blog/ has published a post comparing process automation methods and measuring benchmarks Salesforce Record Automation Benchmarking
Part II compares Single VS Multi-Object Flow Field Update

I was recently tasked with a requirement to display a list of opportunity partners on a custom object related to opportunity. I planned to use a flow to get the opportunity partner records and then display them using the Datatablev2 Flow Screen Component available on this site. When I tried to create the flow, I encountered some issues:
1. The Opportunity Partners object is a legacy object and cannot be customized. I could not create formulas for getting the account name or link to the account
2. I could not use dot notation to get the account name from the account ID in the get records component in the flow
3. I could not use the partner account ID as a filter criteria on a new get records element to get the account records.

I knew I had to create a custom way to get the data I needed to display. Eric Smith referred me to his blog post on how to use Apex defined data types and an invocable action to create data for the datatable component.
How to Use an Apex-Defined Object with my Datatable Flow Component
I create my Apex defined data type for opportunity partners.

/**
* @author       : Tamar Erlich
* @date         : October 07, 2020
* @description  : Wrapper class for opportunity partners
* Note          : This class is called by the GetOpportunityPartnersAction.
* *************************************************
*       <runTest><runTest>
* *************************************************
* @History
* -------
* VERSION | AUTHOR                | DATE               | DESCRIPTION
* 1.0     | Tamar Erlich          | October 07, 2020   | Created
**/
public with sharing class OpportunityPartnersWrapper {

    // @AuraEnabled annotation exposes the methods to Lightning Components and Flows
    @AuraEnabled
    public String accountName;
 
    @AuraEnabled
    public String partnerRole;
 
    @AuraEnabled
    public Boolean isPrimary;

    @AuraEnabled
    public String accountLink;

    // Define the structure of the Apex-Defined Variable
    public OpportunityPartnersWrapper(
            String accountName,
            String partnerRole,
            Boolean isPrimary,
            String accountLink
    ) {
        this.accountName = accountName;
        this.partnerRole = partnerRole;
        this.isPrimary = isPrimary;
        this.accountLink = accountLink;
    }
 
    // Required no-argument constructor
    public OpportunityPartnersWrapper() {}

}

I then created an invocable action that received the opportunity and account IDs and returns a JSON string that can be displayed in my flow table.

/**
* @author       : Tamar Erlich
* @date         : October 07, 2020
* @description  : Invocable method that given opportunityId and accountId, returns a list of opportunity partners to display on the record page
* Note          : This class is called by the Flow.
* *************************************************
*       <runTest>GetOpportunityPartnersActionTest<runTest>
* *************************************************
* @History
* -------
* VERSION | AUTHOR                | DATE               | DESCRIPTION
* 1.0     | Tamar Erlich          | October 07, 2020   | Created
**/
global with sharing class GetOpportunityPartnersAction {

    // Attributes passed in from the Flow
    global class Requests {

        @InvocableVariable(label='OpportunityId' required=true)
        global String opportunityId;
        
        @InvocableVariable(label='AccountId' required=true)
        global String accountId;
    }

    // Attributes passed back to the Flow
    global class Results {

        public Results() {
            
        }
        @InvocableVariable
        global String errors;

        @InvocableVariable
        global String successful;

        @InvocableVariable
        public List<OpportunityPartnersWrapper> outputCollection;

        @InvocableVariable
        public String outputString;
        
    }

    // custom exception class
    global class InvocableActionException extends Exception {}

    // Expose this Action to the Flow
    @InvocableMethod
        global static List <Results> get(List<Requests> requestList) {
            // initialize variables
            Results response = new Results();
            List<Results> responseWrapper = new List<Results>();
            String errors;
            String success = 'true';
            String stringOutput;
            String accountId = requestList[0].accountId;
            String opportunityId = requestList[0].opportunityId;
            List<OpportunityPartner> opportunityPartners = new List<OpportunityPartner>();
            List<OpportunityPartnersWrapper> partners = new List<OpportunityPartnersWrapper>();

// BEGIN APEX ACTION PROCESSING LOGIC
            try {

                if (accountId == null || opportunityId == null){

                    throw new InvocableActionException ('No Account or Opportunity ID');

                }

                if (!accountId.startsWith('001')|| !opportunityId.startsWith('006')){

                    throw new InvocableActionException ('Invalid Account or Opportunity ID');

                }

                if (accountId != null && opportunityId != null){
                   
                opportunityPartners = [SELECT AccountTo.Name, IsPrimary, Role 
                                        FROM OpportunityPartner 
                                        WHERE OpportunityId =: opportunityId and AccountToId !=: accountId];
                
                }

                // populate the Apex defined wrapper type with opportunity partner information
                for (opportunityPartner op : opportunityPartners) {

                    OpportunityPartnersWrapper opw = new OpportunityPartnersWrapper();

                    opw.accountName = op.AccountTo.Name;
                    opw.partnerRole = op.Role;
                    opw.isPrimary = op.IsPrimary;
                    opw.accountLink = '/'+op.AccountToId;

                    partners.add(opw);

                }

                // Convert Record Collection to Serialized String
                stringOutput = JSON.serialize(partners);

            } catch (InvocableActionException e){
                System.debug ('exception occured: ' + e.getMessage());
                
                errors = e.getMessage();
                success = 'false';
            } catch (exception ex){
                System.debug ('exception occured: ' + ex.getMessage());
                
                errors = ex.getMessage();
                success = 'false';
            }
// END APEX ACTION PROCESSING LOGIC

            // Prepare the response to send back to the Flow
            // Set Output Values
            response.errors = errors;
            response.successful = success;
            response.outputCollection = partners;
            response.outputString = stringOutput;
            
            responseWrapper.add(response);
    
            // Return values back to the Flow
            return responseWrapper;

        }



}

/**
* @author       : Tamar Erlich
* @date         : October 07, 2020
* @description  : Test class for GetOpportunityPartnersAction Invocable method
* Note          :
* *************************************************
*       <runTest>GetOpportunityPartnersActionTest<runTest>
* *************************************************
* @History
* -------
* VERSION | AUTHOR                | DATE               | DESCRIPTION
* 1.0     | Tamar Erlich          | October 07, 2020   | created
**/
@IsTest
public with sharing class GetOpportunityPartnersActionTest {


    @isTest
    public static void opportunityPartnersFound(){

        // initialize variables
        List<GetOpportunityPartnersAction.Requests> requestList = new List<GetOpportunityPartnersAction.Requests>();
        String accountId;
        String opportunityId;

        // create test account
        List<Account> accounts = new List<Account>();

        for (Integer j = 0; j < 1; j++) {

            Account a = new Account(
                Name = 'email' + j + '.com'
                );

            accounts.add(a);
        }
        
        insert accounts;

        // create test opportunity
        Date closeDate = System.today();
        Opportunity testOpp;

        testOpp = new Opportunity(
            Name = 'test opp',
            StageName = 'Open In-Progress',
            Amount = 100,
            CloseDate = closeDate
        );
        insert testOpp;

        accountId = accounts[0].Id;
        opportunityId = testOpp.Id;

        // create test opportunity partner
        OpportunityPartner testPartner;
        testPartner = new OpportunityPartner(
            OpportunityId = opportunityId,
            AccountToId = accountId,
            Role = 'Dealer',
            IsPrimary = false
        );
        insert testPartner;

        // prepare request for GetOpportunityPartnersAction
        GetOpportunityPartnersAction.Requests request = new GetOpportunityPartnersAction.Requests();
        request.accountId = accountId;
        request.opportunityId = opportunityId;
        requestList.add(request);

        // run test and assert results
        List <GetOpportunityPartnersAction.Results> results = GetOpportunityPartnersAction.get(requestList);
        System.assertEquals(results[0].errors, null,'Errors not expected');
        System.assertNotEquals(results[0].successful, 'false', 'Success expected');
        System.assertEquals(true, results[0].outputCollection.size()>0, 'Opportunity Partners expected');
    }

}

I then used my new action in the flow to get the opportunity partner records.

I then configured my datatable on the flow screen

Some notes on the datatable configuration:
1. User Defined had to bet set to true
2. The Datatable Record String must be set to the variable returned from the action
3. The column field types must be set for all columns. I set the first column to the url type
4. My first column has special type attributes for displaying as a clickable link: 1:{label: { fieldName: accountName}, target: ‘_blank’}
5. Since this is for display only, I hid the checkbox columns
6. I used the new features available in v2.46 to apply an icon and title to the table

The View All link uses a formula to create the link

Here is the entire flow

And here is the end result

This use case can be easily adapted to display other opportunity related information like opportunity team members or opportunity contact roles.