Yeah, only thing I can think of is the few banking apps that don't have web versions.

I was lucky enough to have all my banking and 2FA apps work perfectly on GrapheneOS. The only app that gave me a significant amount of trouble was iClicker, which my school uses for attendance. That was fixed by enabling Google Play location services, and there was a (fairly expensive) alternative anyway.

I did have to buy a new phone to use Graphene, because I got my previous one as part of a carrier's cell plan, and it had a locked BIOS. Though I think the purchase was worth it, and just moving my SIM card from one device to another was enough to get it working.

Uber/lyft. You can use uber via the web but not lyft. If uber ever stops working on web then thats it.

NFC payments with Google wallet, in theory if your bank provides the service in their app, you could still use this kind of payment, haven't tried it tho.
Also I only found a developer for which their games don't work, it's the developer of guardian tales.

Aside from that, with sandboxed play services there hasn't been any difference since I migrated to GOS.

Indian and Turkish banking apps. Webapps are banned there.

I still have to find that app that does not just run in GOS. There may be a few that I don't know about because I don't use them, but all the ones I use just work.

Granted, most of my daily use apps are FOSS and installed either from F-Droid or from source repo.

Authy

Loads of things that depend on google play services