Whether NFC payments work seems very much dependent on what your bank app is allowing. Some banks in the EU have no issues, so you should check what particular payment system you want to use.
In general, chances are low. Some people use smartwatches as a workaround.
I don’t use smartwatches nor NFC payments with smartdevices. My bank card allows NFC payments directly.
Useless for GrapheneOS then. I’m in the market for a decent tablet soon (on a LineageOS Samsung right now), and effectively I’ll have to settle for a used Pixel tablet. Orelse it’s Linux tablet time, which is probably nonexistant as well.