We scan the PKID and Serial Number of the computer into a CSV file, and send it to the desired email address so you can upload the file to your customers environment through Microsoft Partner Center.

The computer is then sent from our warehouse to the end user. When they start it up, it is registered to their domain and the computer can then automatically start downloading profiles, applications, and programs associated with the user.

Note, this file can only be uploaded to the customer's environment if you are a Microsoft CSP or OEM partner with an established relationship to your customer.
The HW-hash is not included in the CSV file for security reasons and thus can't be uploaded directly into intune by the end user themself.