Apple's 2FA makes things much simpler for users who own multiple Apple devices (very easy to authorize a new iPhone from your iMac or iPad) but if you only have one, it's next to impossible to use reliably. You can't make a backup or use a third-party 2FA client, or a non-Apple device. They don't provide "traditional" TOTP two-factor authentication that you could use in many different TOTP-based authenticator programs.

edit: Mercifully, they at least allow you to enter the 'find my iPhone' section without needing the 2FA code.