Passkey is some sort of specific unique key to a device allowing to use a pin on a device instead of the password. But which won’t work on another device.
Now I don’t know if that key can be stolen or not, or if it’s really more secure or not, as people have really unsecure pins.
That’s the key question. From what it seems, it would replace a password manager with different passwords for each website, but you give Google control of the master password.
It is not for the password manager…
It’s just to connect to the google account.
It is not a service to connect to other ones without passwords.