Using your POS documentation, fetch all the products and options from the business and insert them to Ordering. You have to send business id as "bid" param on the "GET" method. The plugin should fetch the store id and IP, which we have to add on the business metafield that we add before.
You can use products and product suboption metafields to save all the data.
Fetch the product price and compare it with the existing ordering product, and if the price doesn't match, update the new price from the POS to Ordering.