Probably not for much longer though. Several countries, including mine, have already banned SMS 2FA for banking, and it's likely that that will be implemented for all of Europe in the near future, possibly with PSD3. Not that SMS 2FA was ever a good idea in the first place.

But yes banking apps are not mandatory, and likely won't be in the near future either, though the alternatives are treated a bit like second class citizens.

My bank offered that option but not anymore. The use of their app is mandatory now.

Edit to add this anecdote. My bank told me I need to use their app because SMS is not secure, but you need to activate their app using an SMS code!