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.
If that's the case, then a bad actor could spam someone's phone with notifications. All they'd need is a username.
Or, like my mum, you don't read what the notification says and just hit 'OK'. Now you've let someone into your account without realising
Shit. Good point. According to this blog at 1Password, Bluetooth can be used to have one device verify another for a service. So I guess if the public device has Bluetooth, it’s possible 🤷♂️
There's more ways such as scanning a Qr code to establish a connection from the app to the computer, or by presenting a number on one device which must be entered on the other