How to test Android applications with in-app purchases for a developer from the Russian Federation under sanctions?

Question

Android

During development - when I try to test the work of in-app purchases in my own application (from a special account for tests), I get an error that "google play does not work in your country".

And when I test on a device where the main Google account matches the account of the developer (= me), I get the opportunity to pay with a test pseudo-payment card from Google, but in this case, the purchases in the wrapper library I use (qonversion) work very crookedly and test the work in-app, I can’t, and the authors of that library themselves say that you need to test purchases from another account (other than the developer account) ..

Application - in the status of internal testing. The second account is also in the list of testers. I install the application by downloading a signed apk file via google play console - maybe this is the reason?

Why doesn't an app with the status of internal testing, on a device where the main account is different from the developer's account, show the same test pseudo-payment cards? How can they be enabled on that device?

Thanks for the replies in advance!