The difference in friction between "Getting my Yubikey out of my bag" and "Pressing the TouchID button" is enough to keep me on Chrome.
I use fingerprint authentication on a laptop with Windows 10 and Firefox on sites that allow me to use this as the second factor.
There is also a flag in about:config (signon.management.page.os-auth.enabled = true) to make sure this support is enabled.
Initially I found that it wasn’t working, and then I went through troubleshooting mode (disable all extensions) and found an extension that was blocking this from working (I didn’t spend time on investigating why or if someone else had seen the same issue).
This is the Bugzilla ticket in question: https://bugzilla.mozilla.org/show_bug.cgi?id=1536482