If "secure enclaves" are actually secure, companies manufacturing those "secure enclaves" could just log the encryption key(s) at fabrication time to render them useless?
Also, are you saying that even the machines manufacturing them do not know what they are doing ("... secure enclave manufacturing process is done is such a way that even the manufacturer does not know what the key is.")? Sounds a lot like a PR campaign... I would be curious to know how this manufacturing process really works.
Even so, if they do have the UID that greatly reduces the security of the encryption - especially if you are using a short passcode.