Some of those banks may also still support using their own tap-to-pay. Europe has a standardized system for it and many banks support it. Check https://privsec.dev/posts/android/banking-applications-compa... for those banks. There was a major shift to using Google Pay to reduce their development costs but there may be a major shift away from it now.
https://grapheneos.org/articles/attestation-compatibility-gu... should be sent to companies banning using GrapheneOS via the Play Integrity API. They can keep doing that while permitting GrapheneOS in a more secure way. Our users recently convinced several banks to implement it. Swissquote implemented it for their Yuh app and will hopefully do it for their main Swissquote app soon. It would be nicer if they didn't add Play Integrity API in the first place but progress can be made if users leave lots of reviews, support requests, etc. until they realize it's a big issue and either remove it or implement this as a replacement.