Passkeys are an implementation of a public-key cryptography. The service has the public key, you have the private key. The sites don’t give you anything, you give them the public-key which is generated using your private key. https://www.passkeys.com/ explains a lot of it.
If you use a password manager it’s literally no different than passwords. I can use my passkeys on any device through 1Password.
Okay so if the sites actually give you the passkey to manage that’s not as bad as what I remember reading about when passkeys were first announced
Passkeys are an implementation of a public-key cryptography. The service has the public key, you have the private key. The sites don’t give you anything, you give them the public-key which is generated using your private key. https://www.passkeys.com/ explains a lot of it.