The "localised EMP" you mention could simply be a low power microwave oven of same type we have in our kitchens you have to walk through. Waves of that frequency would not harm a person if they were fairly low power, but it would mess up every bit of non-metal-shielded electronics.

If you want to destroy a piece of electronics quickly put it in a microwave oven and hit start (also don't expect to eat from that oven later - plastic residue etc if it heats up that much is probably not safe to eat). This will destroy usb keys and storage on them, SSDs, laptops, smartphones and data on them. The only kind of data safe is magnetic type hard drives, but they become less and less common these days.

You could even make a kind of "wand" similar to what guys at the airport have for pinpointing metal items on people. Wave it around someone suspected of having a listening or recording device - job done.