Unfortunately these days bank apps are required by the banks for "security", and good luck getting anything done without the bank app installed on your phone.
The only other alternative available is SMS but that is being phased out (rightly so) for being insecure.
Currently my bank requires a device where I need to insert my card to get a one time six digit code based on a QR code the banking website serves me that the device scans.
I'm not quite sure why they don't support something like a yubikey with FIDO, but maybe there's a good reason.
Every bank here had that. Now they all require apps.
For the banks I understand. Now they don't have to supply millions of code calculator devices. And they force their apps which they can stuff full of tracking to mine their customers for data they can sell.
It's sad but part of the usual enshittification cycle
They provided you with one? My bank made me buy my own device. It's an online bank, so I'm not sure if using the app allows for better tracking than simply using their normal website. So far I haven't been forced to use an app, so I guess not.
The only other alternative available is SMS but that is being phased out (rightly so) for being insecure.