My bank had NFC payments for years. None of the remote attestation bullshit. I think it used Google's library for doing QR code scans so it wouldn't work without Google Play, but that's beside the point.

Android already supports this, and has supported this for over a decade. The restriction here is on the side of the finance ecosystem. Everyone has congregated on doing Apple/Google Pay because it's cheap and easy to maintain compared to the alternative. Cards companies and banks make deals with Google, just like they do with companies like Apple, Samsung, and Garmin.

Any fintech startup with serious backing can create an Android app that works on any ROM you can imagine. I don't think you'd have an easy time finding investors for this with how much money you need to partake in the ecosystem, but the API is ready for you to implement.