That Silca Pocket Impero Mini Pump looks awfully nice, but IMHO is kinda pricey...

So Op - speaking as a CO2 carrier, if you really must have a small pump

Going back 4-5 years I carried a Lezyne Pressure Drive with me everywhere. I was messing with ultra-thin, ultra-light tires at the time, and as to be expected was flatting pretty frequently, so had to use it a lot more than I'd have liked to, but it did work well. often in less-than-optimal circumstances.

I don't know what's the difference between a Pressure Drive and the Road Drive that a couple of the guys here mentioned earlier, but even though I've contentedly moved on to either tougher tires, or flat-liners, and CO2...

FWIW I'm still hanging onto my Lezyne Pressure Drive pump...