Do you lose the whole play store? Does it even make sense if I use gmail? I like the idea at least. And my 4a isn't getting updates now(on graphene either apparently) which is a shame because I still like it. I used to ise lineage on Samsung devices.

One of GrapheneOS's absolute best features is the sandboxed Google Play Services.

Basically, where other privacy AOSP forks typically offer up to three choices...

- no Google at all

- root and install an extremely fragile FOSS alternative GPS implementation (MicroG)

- root and install the full Google Play Services binary blobs

... GrapheneOS offers option #4: you can install Google Play Services in a sandbox so that they still run, but they don't get root-level access to your system, instead they are treated the same as any other app (so e.g. you get to manage their access to location/storage/contacts etc.).

Note that you don't have to, it's just an option in the built-in Apps menu. I personally run GrapheneOS with no GPS at all in my main profile, and occasionally access my old Gmail/Gdrive accounts via web browser.

One of the things that Graphene doesn't support is Android Auto -- They have stated they will never support it due to the sheer rootkit levels that Android Auto does to the OS. Its a shame they have not found a good work around for it yet.

Does Google Wallet / NFC payments work?

Play store is available, just not installed by default. It also lives in a sandbox so has to ask for permission more than it does under standard android.

I never realized how many permissions the play store had, until I ran it under graphene.