I use GrapheneOS in Switzerland and am yet to find a bank or financial app that doesn't work. ZKB, UBS, Cembra, BEKB, SGKB, WIR, N26, Revolut, debiX+, SaxoTrader, Swisscard, various TWINT apps, YAPEAL and Yuh are all installed on my phone right now and all work. Most of them don't use the Play Integrity API at all and the few that do are satisfied with the minimal level that's satisfied by GrapheneOS.

The catch is that you need Google Play Services installed and for many, you need to disable GrapheneOS' "Secure App Spawning" feature, which often trips root detection heuristics.

I know many Russians living here and when sanctions came in, their accounts became unable to receive deposits until they provided evidence of a valid residence permit. Some have problems during permit renewals as well but overall, it's nothing like as bad as it is for Americans.