I know it's supposed to be for privacy nerd, and they will tell you you shouldn't use Google pay because it's bad for privacy and so on... But it's not the majority of people, most are willing to trade some privacy for convenience.
What i don't like is having companies, google amongst others, siphoning my data and making money out of it, while offering in exchange a service that is becoming increasingly worst.
grapheneos with it's enhanced permissions and profiles is pretty god at preventing these spyware from stealing all my data, for instance you can have give whatsapp limited contact permission and make it run in a secondary profile.
face unlock is a tradeoff between security and convenience that i'd happily take ! But grapheneos doesn't give me that choice...
The problem isn't the OS, it's the payment providers not providing support.