In November I reported on my bank disabling 2FA via SMS, back then it seemed my 2020-2025 experiment of smartphone-free living was coming to an end. But! I found that there are multiple banks in austria (the big ones primarily) that support "Card TAN", i.e. you get a physical 2FA device (free of charge even, looks like a calculator, works across all banks) that you can use for all 2FA needs.
It was quite a bit of work to figure everything out, and my account fees are higher now, but I've switched bank, and it works flawlessly now. Smartphone-free life go brrrrrrrr. (Thanks everyone for your input and ideas back then! <3)