You’re right, it’s not easier than plugging a charger into the USB port. Poor choice of words on my part. But I do think it is a far more elegant solution. There’s no waiting around to charge batteries, there’s no need to carry extra batteries, and the “auto style” 12VDC compressors which are meant to plug into a cig lighter socket are a heck of a lot more powerful, and more compact, than either the Ryobi or the M12 inflators. Speaking of the Ryobi cordless inflator, I have owned one and it failed very soon after I purchased it, and I was extremely careful to follow the instructions and not use it longer than the recommended duty cycle. While I have had good luck with many Ryobi tools, that one is junk. I can heartily recommend the Dewalt portable inflator, but that’s very big and clunky to carry on a motorcycle.
Another idea is to carry a CO2 inflator and then sidestep the issues of electricity entirely.