Thanks for reaching out, I’d be happy to help you.
You can have your own SKU for your products and your suppliers may have their own. So, when the Orders search by SKU is enabled, you can search by the number you have assigned for product SKU (or for supplier SKU).
In your WC Order Page, when entering an SKU or Supplier SKU in the search box, you could search for all the orders that contain products with that assigned number.
Please, note that due to the complexity of this query, it could cause a delay in returning the searched results on dbs with many orders.
Please, let me know if there is anything else I can help you with.