For air on the bike, I wouldn't rely solely on CO2. One CO2 cartridge may fail, or you may find you didn't patch the tube properly, didn't find and remove the sharp thing in the tire casing, didn't seat the tire bead properly meaning you need a second CO2 cartridge. So you carry two CO2 cartridges. Then you have a second flat . . .
CO2 was originally carried by certain racers, triathletes I think, who needed to be able to repair a flat as fast as possible. Most of us aren't racing against time when we have a flat.
It doesn't take much time to pump a tire with a frame pump, and I carry Silca frame pumps on two of my bikes, including the commuter. A mini pump takes longer, but still less than two minutes. Lezyne makes a mini pump that also accepts a CO2 cartridge, if you want to have cake AND cherry on top.