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.
My bank (Monzo) doesn’t even offer an alternative way to interact or sign up except through the smartphone app.
FWIW, Monzo works on Lineage OS with no gapps. I can’t use google pay but I have a card for that.