Attach a standardized handle to every item. Have the robot look for and grab the handle.
The handle should be such that when grabbed by the robot in correct orientation, it can properly support the full weight of the item (or the box/packaging containing the item) + some amount of additional torque incurred while moving.
The handle can either go out with the item or be removed by the robot for reuse. If it goes out with the item, it needs to be reusable/recyclable or represent minimal additional packaging material.
Many small items already have the standard ____()____ hole for rack display. Make it easily recognizable (contrasting border) and give robots a little finger to grab it.
Many light items in cardboard boxes have standardized cut-flap handles. Give robots a little hand to grab it.
Heavier items in cardboard boxes often have handles. Standardize, give hand.
Think of it as pallets for individual items. When shipping items you don't need to determine how best to pack, handle, move, or store them, let alone program a robot to do so. You just use a forklift and grab the pallet. All of the thinking for the other shit for each individual item is done by the people making the individual item.