For nfc payments I think you need to add the card to Google wallet/pay as far as I found out. So that's bit annoying, we are so deep in Google stuff you can't get away easily.
I had a Pixel 6 and now I use a Pixel 8, both of which I had battery problems (they don't last long) and they also get too hot. But unfortunately they are the only ones that run GrapheneOS so it is a sacrifice that I am willing to make. Regarding apps, all the ones I use, without exception are open source and I have no problem with them so far