Or is that video from 2021 is just too old and not up to date anymore?
Correct. At that time, there was no AppTransaction.
I believe that what you are doing is correct. (Maybe you should also look at some properties of the verified receipt object?) I’m unsure what exactly your problem is. You seem to think that verification should fail in development, or that it should succeed only after an App Store login dialog. I’m not sure why you think that. If you think that only because that’s what happened in the old system - well, that was the old system.
Topic:
App & System Services
SubTopic:
StoreKit