"So there'll be a centralised list of all the places I have accounts?"
Only on your own device or application.
You can think of this standard as a password manager, only instead of being a database of passwords it's a database of secure cryptographic keys. How these keys are secured is then up to the device. It could be some snazzy phone-based biometrics (e.g. fingerprint, facial recognition), a yubikey, or a bog standard pin or password.
The point is those credentials are limited entirely to your device and can be extended to test for user *presence* and not just verifying the password.