Good question. I've found radar to be quite useful on mobile or other small screens. When you join a room that has things to scavenge, you will get an icon that looks like this:

it will appear at the edges of the screen so you can see where there's something to pick up. It actually makes it quite a bit faster to scavenge cause you can just go straight to it instead of wandering.
Later at level 27 you are supposed to be able to see what the item is instead of just the ? bubble.