This is an area with the specs contrast with the vendors.

The WebAuthn specs recommends to register multiple passkeys/credentials per device and assume that once a credential is lost it might not be recoverable.

Apple and other vendors using keychains/wallets are effectively offering the option to delegate the recovery of the passkey to the recovery of the account with them (eg: the iCloud account).

In case it is of interest, we wrote a long blogpost on the topic: https://www.slashid.dev/blog/passkeys-security-implementatio...