[kemotep]

The pin or swipe pattern is used to unlock access to the private key that you actually use to sign in with. Much like having a pin to decrypt your ssh key.

The article covers this by suggesting that users should configure multiple devices to the service and at least with Apple’s passwordless implementation you have the option to save the private keys in your keyring to icloud. As long as you can gain access to your iCloud account and restore your keyring you shouldn’t lose access to your accounts.

Additionally, most accounts (like gmail) allow you to make recovery codes that you could backup, write down, and otherwise store someplace offline and safe so if you cannot use your passwordless login you could gain access that way.