It does! Open about:config and switch security.webauth.u2f to true. It'll Just Work.
I've in the recent past modified a barebones Perl webapp to try and understand U2F better, see https://u2fdemo.darkpan.com/
I've been able to log in / use U2F from:
* FF on Windows and OSX
* Chrome on Windows, OSX
* Chrome on Android using either a OTG cable for a U2F USB key, a Bluetooth U2F key, and a NFC U2F key (works if you install Google Authenticator)
* Unfortunately, not FF on Android as I can't find how to enable U2F there yet :/