[phillc73]

> about:config security.webauth.u2f

I still have this set to Value: "false" in Firefox 66.0.5 and it's working fine for Google Accounts.

Edit: I'm pretty sure I registered by Nitrokeys with Google back in 2017 using Chrome, so I'm just referring to signing in with them.

[judge2020]

You could always sign in with any key, you just could only register keys via Chrome.

[phillc73]

I seem to recall U2F sign-in always failing with Firefox for a long time. I remember having to switch to Chrome for U2F and frankly ended up using a different 2FA method for a couple of years because of that.