I carry a powerbank and various USB C adapters so if someone’s device dies I can help them out. It is a lot cheaper and smaller than carrying around seven different cables.
On top of that I carry Tylenol and bandages.
I used to carry a full first aid bag but kept forgetting to restock on supplies.
Leatherman Juice Pro. I’ve used it nearly every day for 17 years and have done tonnes of house and auto repair with it. Also a cotton bandanna. Those things come in handy for cleaning, cooling, tying, bagging, you name it.