Yes but the UX works better much of the time. Downside of course is that you can't sign documents without an Internet connection, if that's something you may need to do. And the fact that you need a phone

That solves one issue, the other being how buggy it can be to use in the browser. The file signing feature is separate software (which has an official Linux port!), but to log into your bank, etc, browsers often pre-decide for you which certificate you want to use and then complain that it's not present. Perhaps it's changed now, I haven't used it much in quite a few years now because Mobiil-ID and Smart-ID have just worked 99% of time.