How do you convert an Apk to an Android App bundle?

[Anke]

@rtlerman

I logged into the test server and used it to create an .aab file. I was able to submit my app using the Google Play Console.

Now I am just waiting for approval before it gets released to the store.

I think it is not / was not a good idea to publish an app (on the Play Store) that was built on the test server.
There are still a number of issues and bugs.

So urgent advice to everyone who intends to do this:
Please wait for the final AI2 update (targetSdk = 30).
See also here.