The benefit is if your PIN was compromised your phone would still be inaccessible, barring them having you physically. It’s another layer of defense. Similar to a yubikey, if someone had your phone but not the extra hardware. Although I think using a yubikey every time I wanted to use my phone would be prohibitively inconvenient.

Also, I don’t think PIN and password would be considered 2 Factor. That’s essentially just a longer password.

Let me clarify: when I meant two factor, I mean both. You need both the print AND the pin to unlock. So its more convenient than a full passphrase (for first unlock) but still requires knowledge not just biometrics.

No, this preserves the phone in an “after first unlock” state. They specifically dont want a phone to reboot or shutdown because then the encryption keys get dumped from memory and require the password to decrypt the keys.

You can disable. You can also two factor it e.g. fingerprint and pin, with also a long password for BFU.