We have created a Shopify WMS that handles everything related to warehousing, inventory, cross-docking, pick-pack-ship, etc. which is fully integrated with Shopify Admin API. Many of our customers want to be able to create the purchase order (transfer in Shopify) within SKUSavvy (our platform) and then have the information relayed up to Shopify (same with cross-dock transfers).
It seems Shopify is holding onto this API simply to keep it as their own competitive advantage over any other apps within the marketplace since this should definitely be available to app creators - it would open up a whole new avenue of predictive orders, easier purchasing, and smarter transfers based on order volume, etc.
Can anyone from @Shopify fill us in on when or if there is a plan to release this? We would be happy to be part of a beta program for this as well 🙂