Facebook announced on March 18 (local time) that it will support security keys in the Android and iOS Facebook apps. Facebook itself has been dealing with security keys since 2017, but until now, it was not available in mobile apps, and code verification was required with an authentication app and SMS.
The physical security key used for two-factor authentication when logging in is considered to be more secure than other authentication applications or code authentication than the physical device required. The actual use of security keys has been widespread, and in recent years, the Twitter mobile app is responding to several security kings.
Security key registration can be done in the settings menu, secure login 2-step authentication settings. In the case of the iPhone, the security key cannot be used for USB Type C and Type A, but NFC or Bluetooth type can be used. Related information can be found here.