Support was first offered in May, but now Google suggests it as the default choice.
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)
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.
Yes. Unless there was a way to share that key between devices. I know Bitwarden is working on a vault for keys but it's not released yet. It was due out now so I assume it's delayed.
Apple is quite dogmatic in that their implementation demands cross device syncing.
It's definitely possible to have such an implementation and those will be the most common. You take a very small security risk for a huge convenience factor.
For the more paranoid, device-bound passkeys do not sync. If you lose the device, you will need to go through a recovery procedure.
Each to their own but cloud syncing and MFA are a bad mix in my eyes. It has a "who watches the watchmen" problem and it somewhat defeats the point of having a trusted factor when you have an untrusted one on "someone else's computer".
The person you had replied to originally commented on not wanting to have the possibility of everything being broken by losing a single device. I think that's important that everyone realize that some sort of a backup plan is needed, whether that be back up codes, saving the original QR code, or being able to use multiple devices to authenticate.
At any rate, I should have replied to someone else. Sorry for any confusion.
And you're very much right. There's a growing problem in consumer perceptions of modern security methods and how they should be applied. Much more time is spent justifying the convenience of proposed solutions, and not nearly enough time spent understanding what the scope is of the attack vectors that lead to these things needing to exist in the first place.
And further, why some of these conveniences - much like the reused-everywhere super-long password of yesteryear - are a danger in themselves.