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, not really.
Even if you want to target a specific user, it doesn’t become necessarily easier.
Unless you happen to target an individual that combines good password OpSec with shitty phone OpSec.
But I would expect those to be a minority.