I have found out recently that it's possible to add call recording to modern android versions by using shizuku with some 3rd party apps. The one I like the most is Call recorder by skvalex from callrecorder.skvalex.com/get . Tested on android 16.

However this is not yet tested, I'm also thinking it might be doable to repackage the OTA image by adding BCR (basic call recorder) as a system app using github.com/chenxiaolong/avbroo…

This sounds kind of scary as I don't want to break security of my @GrapheneOS install. But I'd enjoy having BCR as a system app.