Not using any play services or g-mail.
I use busybusy for work, it says I need the play service but it works without it. My credit Union app works fine.
I never got into using my phone to pay, so haven't tried that.
I had Calyxos and switched away from it also.Really like the Grapheneos.
Google pixels seem to be good hardware. I'm going to buy an extra 7,8,or 9 pixel. Not sure if newer pixels will stay as useable.
Some apps require google play, like android auto and maps.I'm using grapheneos with open street maps, so I don't think there would be any problem with that.
There is a work around to load some apps that require google play with out a google account. I'm guessing that is what would be affected.
Grapheneos has a wonderful how to install procedure. I did it with a Linux Debian machine. It took several tries to get the bootloader right, part of that was I didn't know what I was looking for. Once your phone has the red triangle in the bootloader of the phone, the installer should recognize it, and the installer was awesome from there.
Propaganda.