These bicycle pumps work well enough that my 12V compressor got moved out of a car and stored in a corner of the garage years ago.
I have a 12V compressor by Fortem that lets you connect the pump to the tire, set the desired pressure on an LCD screen, and hit the start button. It pumps the tire up to that set point and stops. I have found it very convenient.
I can see how that would appeal with a small 12 V inflator like the one I used to have, which took so long to air up a tire that I really wished I could walk away and do something else meanwhile. More recently, I have a 2 CFM compressor hardwired in and set to 60 psi, using the spare as its tank. (Which means whenever I need the spare, I know it's going to be fully inflated at 60 psi! I was always really bad about regularly digging it out and checking that.) But I have a Gen 3 liftback; finding the space (or a spare) might be a lot harder in a Prime. Filling a regular tire from that goes fast enough that I don't mind just squeezing the trigger till it's done; it doesn't take minutes like the little inflator did. To be honest, since I installed that four or five years ago, I've found it so convenient that if I had a different vehicle without the space to install it as above, I might even consider something more radical like installing it under the floor or under the hood or something.
That is one of several reasons I now use a bicycle pump instead of the 12V pump that has since been stored in the garage corner. The bicycle pump is much quicker. Maybe some other folks have selected a better or quicker 12V pump model. But then I wasn't resourceful enough to think of your even faster spare-tire-as-pressure-tank solution.