I doubt you get many in the yard. Nails usually have to be "set up" by one tire and then run over at speed to cause a puncture. Slowing down on gravel roads is one of the pest ways to reduce punctures but few of us have the patience.

That said I've used an electro magnetic bar on a skid steer that picked up a lot of stuff and I only had to hit a switch to drop things. It was 120 volt and we used a standby generator that rode on the forks to power it, Rube Goldberg!