Pay securely with an Android smartphone, completely without Google services: This is the plan being developed by the newly founded industry consortium led by the German Volla Systeme GmbH. It is an open-source alternative to Google Play Integrity. This proprietary interface decides on Android smartphones with Google Play services whether banking, government, or wallet apps are allowed to run on a smartphone.
I agree it would be good to have third party integrity checks to not require Google Services etc. as part of the chain.
In GrapheneOS, many Google Play integrity check pass, but payments still do not work. You are notified when an app uses the integrity API, but probably only because they have spent a bunch of work sandboxing Play Services. This is what you see when you look at those details:
I guess the obvious problem is that so many apps rely on Google Services, such as for payments, opening the store, checking for integrity etc. On stock android, you can’t pick and choose these services separately or use third party ones, unlike using a third party keyboard, for example. Everything is one big proprietary, data guzzling lump.