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.
Does it need play and/or services?
Yes; but I’m not logged in to any Google accounts.
It also works with MicroG (although the GrapheneOS guys don’t recommended using that).