Passkeys are built on FIDO 2 standards, working across different operating systems and web browsers. You can use passkeys that have already been initialized by signing into your iCloud Keychain or Google Password Manager.

Since passkeys are in part stored in a public server, access to the account that the private key was store in is essential to establish a passkey on a new device.

For Apple Users

For Apple users, passkeys are saved in iCloud keychain, therefore, when you get a new device all one has to do is sign in to their iCloud account. This will setup the passkey on the new device.

For Android Users

For Android users, passkeys get saved in the Google Password Manager. Sign in to the Google Account in which the initial passkey was created and the passkey will be active on the new device.