It seems that Passkeys generally require a biometric scan of some kind. I would prefer a level of privacy where I am not providing images of my face or fingerprints to unknown agencies on the cloud.
I could not find confirmation that biometrics are only stored on the device. In fact, I did see that iOS does at least part of the biometrics in it's iCloud keychain.
Maybe I am not quite understanding how this is going to work, but from what I understand, third-party password managers can integrate into this, and they would not require the biometrics to leave the device.