You can use both hardware bound passkeys (where you may not even be able to read the secret so you probably would want to add multiple device passkeys to a site)
or shared passkeys (where the private key can be synced through something like a cloud service across your devices, see Bitwarden, iCloud)
or shared passkeys (where the private key can be synced through something like a cloud service across your devices, see Bitwarden, iCloud)