Installed grapheneOS on my pixel (finally) the other day. Actually was loving stock, until it got corrupted due to a bug. Had to factory reset to boot up again. Anyway, used that opportunity to install GOS.
NGL I do miss adaptive features and now playing, but I am liking GOS more and more day by day. Better battery life despite not having adaptive features, more security options like sensor permission and scopes, auto reboot if not unlocked feature and all that.
I use GPay and my bank app on a secondary profile. works seamlessly. Some UI improvements and adaptive features and it will be on par with the stock pixel experience itself.
There are very few apps which don't work with GrapheneOS assuming you install google services. There's hardly anything specific about grapheneOS which makes it incompatible, its just that some apps don't like when google services are not available. But the combination of user profiles and compatibility layer with Google services makes the vast majority of the apps work.
Edit: user profiles are not necessary but they are what can help isolate google services from all other apps for instance.
I know, I use GrapheneOS with 6 profiles (only 2 have Google services), but some apps like Android Auto require tight integration with OS which is not possible with GrapheneOS. I thought GPay was one of them.
I just tried it, technically the app works but disallows contactless payments, which is like 97% of the reason for the app, so…