[microtonal]

Correct. I am using my Dutch bank and credit card apps without any issues. Someone linked the curated GrapheneOS banking list already. If your bank does not support it, you could either contact them. If they require remote attestation, this can be implemented for GrapheneOS as well:

https://grapheneos.org/articles/attestation-compatibility-gu...

If the bank is very hard-nosed about it, you could consider keeping an old iPhone or Pixel (because long security updates) for banking if it is practical to do for you. 95% without big tech is also a big win. Of course, if you need to have it with you at all times, that might not be a worthwhile option.