For all the "My Banking Apps don't work", I'd raise one question: Do you really need access to banking apps on the go? I get that it can be handy and maybe you legit do, but I'd wager most people don't really do. If you can pay by phone you can pay by card and the card has less potentially to weirdly break. And if your bank demands a phone app to be used, you can always have a cheap stock android lying around at home…
Not strictly, no, but it's useful to be able to relatively-quickly check my balances (and possibly shuffle funds around between checking/savings and my credit-union-issued credit card). I could use my credit union's website for that, but it's faster to open the app and scan my thumb.
Thankfully, my credit union's app has no issues with GrapheneOS, aside from needing to enable “exploit protection compatibility mode” to keep it from crashing on startup.