Most of the apps include a login feature, where the user should enter his username and password to be able to sign in.
However, passwords are easily forgotten and could be phished by hackers, and some apps force users to provide a strong password, which would be easily forgotten in the future.

Using Biometric login provides a more secure and easier way to sign in; however, it is still limited to the device itself, so if I'm using a platform that provides a mobile application and website, I can be signed in with the mobile device, but I can't be signed in with biometric on the website.

Passkey provides a seamless sign-in experience using biometric fingerprint or face recognition across all platforms, including mobile and websites.
With passkey, the user will have all sign-in options in one place, e.g., normal username and password, federated sign-in (such as sing-in with Google), and biometric. Which makes it easier and clearer for the user.
Passkey is new in Android 14 and has backward compatibility with Android 9, which will make it widely used in the future.