I remember seeing something like that recently on the internets. Except it was definitely not a 'bolt-on' device... it was a hub that powered a self-contained pump as the wheel rotated... again, not to inflate from zero but to counteract gradual loss, and possibly help keep the tire inflated longer with a puncture.
Pumps take energy, though, and we humans have a limited supply... and it would probably be more handy to have a hub dynamo... and pump your tires up at home.