Could we instead use smartwatch Bluetooth or NFC (probably better, I don't like the long range of Bluetooth for something like this) to unlock sites instead of

Could we instead use smartwatch Bluetooth or NFC (probably better, I don't like the long range of Bluetooth for something like this) to unlock sites instead of these USB keys? Does the FIDO Alliance support such a protocol? I know Android 5.0 supports that but it's only for unlocking the phones (and Chromebooks I believe). But what about sites? Or is that too risky compared to an USB key?