CO2 works fine. I've never had a problem inflating a tire with it on the side of the road. One 16g cartridge is enough to inflate a road tire to an acceptable pressure to ride it home (probably not 110psi).
There are some really cheap inflator heads out there that are poorly designed and may not operate the way you expect them to. It's worth spending a few dollars on a decent one, and practicing once in a while at home to make sure the inflator works as expected so you can get the hang of it.
I haven't carried a mini-pump in years, but I do carry a cell phone and am prepared to call an Uber if my roadside tire inflation skills somehow fail me. My flat kit includes two CO2 cartridges, an inflator head, a spare tube, two tire levers, a mini-tool, a patch kit, and now a tubeless tire plug kit. This all fits into a small saddle bag.