Google will start automatically enrolling users in 2FA (aka 2-Step Verification or 2SV) to confirm their identity by tapping on a Google prompt on their smartphones whenever they sign in. The move is meant to remove the “single biggest threat”” making easy to hack: passwords that are hard to remember and
Source: Google announced that iPhones running iOS 10 or later could be used as security keys to verify sign-ins on Chrome OS