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.
Also - and I realise this might be contentious - but I’d suggest one that takes normal batteries. Mine takes 4× AAA.
With Eneloops (or similar low-self-discharge rechargeables), can have a 2nd set that gets you back up and running in under 30 seconds, and if you get really stuck they’re sold in every corner store in the world (heck, throw a pack of Li-FeS2 batteries in the emergency kit, 20 year shelf life).
No worrying about having the right charger cable (commonly a Micro USB, something I don’t tend to carry anymore), or remembering to charge the thing lest it go flat right in the middle of what you need to do.
Mine tend to be AAA models, which works out since I also often have pen lights around.
One thing I have done in my car is attach a rigid MOLLE mount on the sunscreen and then put pouches with a pen light, small knife, lighter, and pens. The kinds of things you always need and often carry but sometimes aren’t quite sure where they have fallen.