Make sure to print out some backup codes. Also I have two Yubikeys authorized for each of my U2F/Webauthn accounts. Fortunately managing multiple hardware keys is much easier with U2F/Webauthn than with TOTP... at least with Google/AWS/Github, you can add a new key at any time, while with TOTP I had to generate a new TOTP secret and update both keys at the same time.

Yeah, that seems like the best bet - either hardware key or TOTP (because, although hardware keys are better for security, not all users will have one - cf. myself), and then store your backup codes in a password manager.

I would assume that GitHub support would be willing to provide some out of band authentication to allow someone to recover an account if all other options had been exhausted.

I personally hope they dont.

Time and time again it's been shown that one of the weakest links for account security is customer support. It's pretty trivial to gather enough information to impersonate someone well enough for most support reps to believe it's actually you.

It's also part of the reason why SMS is so insecure, because legally most phone companies can't not allow you to transfer your number, and the ways they can verify you are you is limited.

If they do allow support account recovery, I hope they allow the ability to disable it for those who don't want the extra attack vectors.

That's the whole point. We do not want that. This leaves us vulnerable to attacks where they take advantage of the support person naiveness.