Google has finally added native W3C WebAuthn support for Google Accounts on Apple devices running iOS 13.3 or a later version. What this means is your iPhone now offers native support for physical security keys to authenticate Google account credentials.
Now available for both personal and work Google Accounts, support for physical security keys first arrived with iOS 13.3. But so far, users had to mandatorily use Google’s Smart Lock app and rely on a Bluetooth-enabled alternative. Google has now released native support for the API in iOS, allowing the usage of a wider variety of security keys.
If you have an iPhone, you can now use Bluetooth and NFC-based options such as the Titan Security Key, a Lightning security key such as the YubiKey 5Ci, and a USB-C security key on an Apple device that has a USB Type-C port. Also, you no longer have to download the Google Smart Lock app to use a physical security key on your iOS device.
Source: Google Blog