A notable mention is https://ubports.com/en/ which is different from postmarketos in a sense that ubports uses old kernels with heavy patches. That means: good support for things, but difficult future.
PostmarketOS uses the newest kernels and tries to integrate their patches into mainline kernel, so that the reliability is maintained with all kernel developers.
You should consider changing bank if they don’t provide a regular website with at least the same functions as their app.
Most banks these days need their app as well to log in to their website because of forced two factor authentication
Ah yes, so easy. Just change banks bro.
Sometimes I wonder if there are any acual adults using Linux. Lol
Actually, what is hard about changing banks? I give my bank info to as few entities as possible. And almost all of them would take a few clicks and possibly a few days to verify some tiny transaction and I would be done. Changing credit cards is far harder. But also. Why are you using the banks app on your phone. That phone is probably the least secure electronic you own. The attack surface on that thing is absolutely huge.
The new bank will happily organise anything for you, and if not, it is not the right bank, because they clearly don’t want you as customer, like this.
Customer support generally gets worse as you are longer at the same bank because you are more and more less likely to switch your bank staying at a bank. They invest in the customers they see risks of loosing or see a change of winning the most.
It could be up to hours of mild inconvenience!