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.
Multi tools are great for a a lot of purposes. A more oddball one that has gotten me many thanks is a high quality, 20a, 10ft extension cord with 3 outlets. Not a power strip or anything, just 3 outlets. Used it in airports many times to split the power at rare outlets. Helped friends running a stand at a a farmers market when there were literally 1 ft short of being able to plug in. It’s been useful enough times it just lives in my backpack.