> For U2F there's nothing to be in sync: each key is added individually, and you don't have to add all of them at once. I.e. if you register the key on your keychain at work, you could later add the backup key in your home vault.
The challenge is remembering to enroll using your backup device. Also, ideally your 2 devices would never be in the same room as each other, otherwise you are at risk of something like a fire destroying both.
The challenge is remembering to enroll using your backup device. Also, ideally your 2 devices would never be in the same room as each other, otherwise you are at risk of something like a fire destroying both.