Starting today, you can activate a security key on your iPhone to help protect your Google Account. Security keys are an important feature of the Advanced Protection Program, because they provide the strongest protection against phishing attacks. The security key in your phone uses Bluetooth to verify your sign-in on Chrome OS, iOS, macOS and Windows 10 devices without requiring you to pair your devices. This helps protect your account on virtually any device with the convenience of your phone, Googles Smart Lock app.”]
Source: https://security.googleblog.com/2020/01/have-iphone-use-it-to-protect-your.html