> An attacker can simply send your email address to a legitimate service, and prompt for a 6-digit code. You can't know for sure if the code is supposed to be entered in the right place. Password managers (a usual defense against phishing) can't help you either.

Roughly the same security for password-login with email recovery. The only difference is that this makes the attack surface larger because the user is frequently using email.

The only secure login is through 1. a hardware device and 2. a solution where both the user/service are "married" and can challenge each other during the login process. This way, your certificate of authentication will also check that the site you are connecting to is who it says it is.