We're currently on Desktop Enterprise with Advanced Inventory, and this feature being "on the roadmap" for the last 3+ years is the one and only reason we can't switch to QBO (and as a result have had to invest thousands of dollars in remote server and software configurations to sync data into QB Desktop). Having seen the power and investment QB has put into its Desktop Inventory and Purchase Orders, I don't understand how even the basics have not made it into QBO at this point. We work with hundreds of vendors each year, and every single one requires THEIR part number on a purchase order, not just our SKU. Oftentimes, customers will come looking for something by the Manufacturer Part Number, not your company's SKU. Desktop has Manufacturer Part Number field AND Purchase Description in case you're purchasing an item differently than you're selling it. 

Most businesses work on a simple model: you buy product and you sell product. HOW has something like Enhanced Integration with Hubspot made it to the release calendar, but adding the most fundamental fields of purchasing has not?