As an ISV, we are using PowerBI embedded using app owns data approach. The app has a service account in our AD, and that service account has permissions on our PowerBI reports.
Using that account, we generate an embed token to show the PowerBI report to our application users (that don't have an AAD login).
However, when we include a PowerApp tile in the report, the user gets promped to log in, even when our service account has access to this PowerApp.
Slightly related PowerBI idea:
Microsoft Idea · Powerapp in embded power BI with authorization in node.js code