Since you’re on grapheneos you could always set up the 2 factor unlock when using biometrics. You would then unlock your phone using fingerprint and a pin. This way even if you’re forced to unlock the device they’d still need your secondary pin to unlock. The pin can be much shorter than your main password so its still fast to unlock.

Privacy policy says they keep logs of browsing data for 6 months.

I’ve had no issues personally with my banking apps. Most require sandboxes gPlay to be installed but there was no need to be logged into google for them.

Not sure now up to date this list is now but check out this site: https://privsec.dev/posts/android/banking-applications-compatibility-with-grapheneos/