Unlock 1Password With a Passkey: Now in Beta
Passkeys are a fast and secure alternative to passwords. 1Password is launching a public beta that lets you create and unlock an Individual account with a passkey. Read more to get started.
.
What is a passkey? Is it a file saved to a decice? Can it be on multiple devices? How do you set it up on your first device? What if you lose your device? Do you need your first device to add it to a second device? How is that different than a text field saved to a password manager?
https://www.passkeys.io/technical-details#passkeys-under-the-hood
They are a form of public key cryptography.
The private key never leaves your device.
You can't really transfer them between devices.
A lot of your other questions depend on the service. Generally you can still opt to use a password+2FA instead even if you have PassKeys enabled so adding one on a second device would simply require logging in with the password first or authenticating from another device if the service supports it.
I don't use 1Password so I can't speak to their setup.