88er_from_nam does google wallet/google pay and google messages (rcs) work with sandboxed google play?
Google Pay wouldn't work for contactless payment as it needs a positive device verification therefore, but Curve Pay is a good alternative and works very good for me, but availability depends on your home country.
RCS should work, but only with a Google account and if you want to use all the Google stuff again, you should consider, if GrapheneOS is really the right thing for you. Im sure, that Google reads every message, encrypted or not, even as Meta and similar do this on their systems.