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.
AOSP is Android in barebones so apps “work”, the thing is that most apps need services that are developed by Google on top of AOSP (google maps api, notificacion services, google pay) and that are hard to replace because they need costly infraestructure or years of constant development. On top of that Google is promoting/forcing the use of Google Play Protect so more apps need that layer now