I never understood the banking app thing. I can use my banks website to manage my finances, using my built-from-source Gentoo Linux computer. Why must a phone then be totally locked down?
Only because hardware attestation is not yet a thing on desktop browsers. Google and Microsoft are working hard to change that, though.
I came to my bank to discuss a mortgage and I saw them log into their environment. A nice Windows environment with bright blue title bars and big red X buttons. In other words, Windows XP for which even the long term extended support has long since passed.