Firefox lets you enable software tokens, and disable USB tokens: in about:config, set

    security.webauth.webauthn_enable_softtoken=true
    security.webauth.webauthn_enable_usbtoken=false

then the registration will go through without needing a hardware token.

Err... and how is my software token generated? Where is it stored? Can I move it around browsers, e.g. use it with my Mobile Firefox after I generated in on the desktop?

In other words, I can't use it in production (yet), because I'd need to ask users to change browser settings for it to work. That's disappointing :(

You can use it in production for users who have hardware tokens (and it is used in production by many sites for 2FA). But if you mean you can't _exclusively_ use it in production, then yes that is probably true since not all users will have authenticators (yet).

It’s almost like the designers thought - we are so damn close to killing the password, but, nah, why bother.

If you're using windows I think you need to setup a pin or the hello auth method. Once windows has a quick way to authenticate you it'll offer that when you register

Firefox mobile allows using fingerprint.

I recently implemented this in a library (https://pypi.org/project/django-webauthin/), and Firefox mobile (at least for me) won't log you in if you're using resident keys. Registering the key works, but not authenticating. It's odd.