[spacedcowboy]

You don’t need to have your second device to get past 2FA in a disaster scenario. You can phone up Apple Support and as long as you know the code you use to unlock your old phone (which is a reasonable ask), you can regain access to your iCloud account, and hence to your iCloud Keychain/devices.

Apple don’t know your unlock passcode, so they can’t do it for you, but this is designed to cover the “my house burnt down with all my devices inside” type of scenario, or your own “I no longer have access to a device”.