I would add shelves, pegboard, and a rod or small shelf under the cabinets.
Could you put shelf’s on the wall
Try using the space above the cabinets -- with baskets that hold kitchen items that you use infrequently
Some very practical ideas here: https://www.forbes.com/sites/houzz/2015/02/03/10-big-space-saving-ideas-for-small-kitchens/#56109f5b6c4d
You could set up an area in the house elsewhere and make it into another cabinet for storing food, etc. I had a friend that transformed a coat closet into more storage for her kitchen, or a space downstairs may work.