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.
No it’s literally in the spec. Passkeys are designed for cross device synchronization. You have to go out of your way to make it local only (or use a different webauthn spec like physical security keys)
Removed by mod
The original spec is resident keys including TPM protected or hardware token protected keys designed to be impossible to copy. That’s why there’s a distinction.