Yeah, all of them claim that... but I just walk into the bank and say I don't have an Android or Apple 'smart' phone, only a Linux pocket computer (Librem 5). So they could either buy me a duopoly smart phone, or let me log in via web browser with physical token or other MFA... or I take my money elsewhere.
I have several bank accounts in 2 different countries, and all of them backed down either gave me a hardware token or let me use the web app.
If an institution is holding your money hostage until you are forced to run their surveillance-tracker-infested malware on your personal device, that is a much bigger problem than what OS or device you choose.
That's why I understand the appeal of permission-less Open Source freedom money like Bitocin (BTC) and Monero (XMR).