@anon28734771 is referring to AOSP’s host-based card emulation API, which allows banks (or any app) to implement NFC payment support directly in their own apps, not the old (circa 2015) “Android Pay” app which became Google Wallet and/or Google Pay.
I don’t know of any American banks which implement this feature on Android personally, but I understand it is commonly used in the EU. When that feature is used, it should directly interface with your banking provider without any (Google) middlemen.
I’m not sure why this functionality wouldn’t work already on GrapheneOS though, so it does seem a bit unrelated to this thread (but I haven’t tested it).
I absolutely love that Wikipedia had to create a flow chart to decipher Google’s ridiculous naming schemes:
