Last time I tried (granted, years ago), BankID was still relatively straight-forward to set up and use on a PC. Not all sites support the flow, though.

Authorities should also still accept alternatives like Freja (if there's anything they won't close the door on it's making it straightforward to pay your taxes, I guess).

I'm far from happy wit the situation and would prefer that authorities take an open standards-approach compatible with FLOSS. But it's also not as terrible as it may seem at first.