Put the chicken wings in a coated inner pot. It's best to spread out the bottom of the pot and put in all kinds of spices. It's very simple and won't paste the bottom.
That iron shelf works well. You can put a plate or bowl on the shelf to put vegetables. Just put the iron frame in the pot and pour a small bowl of water under it. The steam in the pressure cooker can't get out, so there is no need to evaporate a lot of water.
I have steamed fish and crabs on the grill, which is not bad. In fact, anything that can be steamed can be cooked in a pressure cooker.