Many bank apps, and apps to interact with official state services, usually depend on Play Services. Sometimes it is all banks in one's country, so no, one can't just "switch to another bank" as US Americans on HN often assume.
İ think this is the case in a small number of European countries and really it should change. İn two asian countries İ do business in, and one middle eastern one, the bank apps now provide a third harmonyOS alternative. The American banks I've used don't require an app, and HK banks will provide a digital token generator which is actually my preferred way. İ think that if it's the case you are tied to one foreign third party company to do banking it should be really something you protest about strongly and change it.
Can't speak for all countries ofc, but the happy path isn't just the US. I've heard positive reports in Europe where banking apps work without Play services more often than not, and if it doesn't some banks will actually change implemented policy once a customer complains.
You can always just have a burner android phone in a drawer somewhere and operate it via remote desktop from a device you actually control