I would like to confirm the need of such feature (to check the quantity on hand through the mobile app). In fact, checking on hand quantity through the mobile application was one of my major reasons to joint QuickBooks, unfortunately it was not available.
It would be appreciated if you may share our request to add this feature with the development team at QuickBooks.
Our team is always working hard to add more features to the program. Your feedback will help us in making QuickBooks Online more user friendly and meets every business needs.
As mentioned by my colleague, you'll want to visit our QuickBooks Blog. All new features, updates, and innovations will be posted there.
I've added some articles for more info on how to set up, track and adjust inventory in QuickBooks Online.