Give them their own list of ingredients for common items they love to eat. Draw pictures next to the words if necessary and review it before going into the store. Enjoy watching them locate the items and cross them off their "list".
Split the job- You get the items off the shelf and they put the items in the cart. Talk about a good place to put small items vs big items, where to put the eggs vs the laundry detergent.
Have fun with produce! Add number concepts. For example, we need "3 apples". Help them count out the number of items and put them in a bag. Discuss what it means when food is bruised, rotten, or unripe.
Introduce and explain functional categories- frozen food, produce /fruits and vegetables, canned food, cleaning products etc.
Unpack together! Split the job- you hand them the items and tell them where they go (fridge, pantry, cabinet etc). Then switch! And have them hand you the items and tell you where they go. (start with only 1 bag of common items, so the child feels successful)