Are there any FIDO security keys that explicitly support backing up and restoring their master secrets? I would love to move from Username + Password + TOTP but my current workflow requires that I am able to regain access to my digital accounts using nothing but a few page paper backup including core service passwords & exported TOTP secrets.

There are some software tokens (Wear OS watch, Android phone), but they are purposely not exportable from the Android Keystore.

https://github.com/herrjemand/awesome-webauthn#software-auth...

There was mention of a secure backup proposal, but it doesn't appear to have been touched after being a draft for a year:

https://github.com/Yubico/webauthn-recovery-extension