The initial inventory entry can indeed be tedious. There are a couple of tips that can help with the process that you might not be aware of.
When entering an item only the name, quantity, location, and expiration are required and the quantity is always defaulted to Q 1.
If you have more than one location in use, but you are entering several items into the same location, set the 'Remember Last Location' switch and Prep & Pantry will automatically select the last location used.
If many of your inventory items are non-food items, disable the expiration date requirement under Settings> Settings and Options.
If you are adding an item that has multiple locations or expiration dates, use the Quick Add. (It is located at the bottom of the screen on iOS, top of the screen for Android.) Quick add saves you from having to scan the same item over and over again.