I use GrapheneOS. But yeah the contactless phone payments cannot work. Otherwise the installation was straightforward (there's a web/easier version) and it's a "hardened" version of the AOSP (Android Open Source Project). You can still use Google Play but it doesn't have the same permissions (by design) as on Google stock.
I should add, if you want to go back, last time I checked Google provide stock Pixel devices Android OSs to reinstall.