I use the 'Yubico Authenticator' (like Google Authenticator but you have to connect to the Yubikey via NFC for it to reveal your login codes) if I need OATH-TOTP, this has nothing to do with U2F.
However the docs in your second link does indicate that their is some new interoperation between Google Authenticator and U2F. It seams that they use Google Authenticator as a stopgap until browser support the system directly. Pretty strange. This in turn has nothing to do with U2F.
I can not test this stuff very well because I use a Yubikey NEO that is to old for the U2F NFC and a Yubikey 4 that has no NFC. I really hope release a Yubikey 4 with NFC soon.
I use the 'Yubico Authenticator' (like Google Authenticator but you have to connect to the Yubikey via NFC for it to reveal your login codes) if I need OATH-TOTP, this has nothing to do with U2F.
However the docs in your second link does indicate that their is some new interoperation between Google Authenticator and U2F. It seams that they use Google Authenticator as a stopgap until browser support the system directly. Pretty strange. This in turn has nothing to do with U2F.
I can not test this stuff very well because I use a Yubikey NEO that is to old for the U2F NFC and a Yubikey 4 that has no NFC. I really hope release a Yubikey 4 with NFC soon.