I’ve got one that isn’t manufactured anymore so I’m not a big help there, Costco has several, and told me that some even have an air compressor.

This is a long way of saying an air compressor might be small enough to carry around and be potentially useful

A jumper battery that doubles as an aux phone battery would be worthwhile to have, because it has two functions, essentially. A telescoping magnet and or grabber is great for things that fall.

Anything else is bigger work steps, I think. Maybe a Bluetooth obd scanner? Though I don’t think strangers will let you plug into their car, typically.