When your inventory is full and you go over a can of soda, there is an option to "Pickup Can". When you do, the can goes into your hand. Unfortunately, you cannot interact further with that can unless you have a spot in your inventory for it. This is incorrect. You can hold a second gun in your hand and use it even though there is no inventory slot open for it to occupy.

We should be able to pick up food and still have the option to eat it, open it, fill it (if it is a canteen or bottle), and the like. It should not require a spot in inventory. It is already in your hand.