Desktop mode is fully functional. NFC works fine and there are tap-to-pay options available. Your bio implies you're in Norway so there should be multiple tap-to-pay options including Curve Pay compatible with GrapheneOS. Norwegian banks may also have it themselves since many European banks didn't move to Google Pay, although others did. Google Pay doesn't allow using GrapheneOS since it's not Google certified and it checks that via the Play Integrity API as do ~10% of banking apps.