The problem is that the PIN is always dominant over Face ID or Touch ID. Face ID doesn't work? Use your PIN. What happens if you use local 2FA and your Face ID

The problem is that the PIN is always dominant over Face ID or Touch ID. Face ID doesn't work? Use your PIN. What happens if you use local 2FA and your Face ID doesn't work? You can't enter the PIN, because that would effectively render 2FA useless. This would probably require some master PIN, which makes things more complex, and increased complexity correlates which reduced security.