Create a plugin that add the Ordering order to the POS system, using the product code of POS which added as the product meta fields.
Preorder
If the POS accepts the preorder and available in the API, then if the user places an order using preorder from Ordering, it will send to the POS as a preorder.
Change to accepted by business
If order injected correctly to the POS change status to accepted by the business.