[Catfish]

This is only completely theoretical, of course. Any resemblance to real life events or people is purely coincidental.

The EMP "device" mentioned does only work once, not continuously. It has to be overcharged to generate an impulse strong enough already for a range of 30 to 50 meters. So it will not jam continuously, but only for a second.

It is said that someone was able to fry a car radio from a distance of 20some meters, to get rid of one of those "thumpmobiles" cruising around at four o'clock in the morning. No idea what it did to the rest of the car's electronics. It can also burn skin if it worked for a longer time, but it does not.
Dangerous, no doubt. From permanent blinding (expositioon to eyes) to actuating airbags, brakes etc. Car electronics should be safe, but.. no guarantees.

So, speaking of drones it has to be closer than it will usually be, to get it to work. And it is probable that the targeted electronics will be destroyed, not just jammed or disturbed.
You could observe what happens to the electronics if you put an aluminium strip in your microwave. I advise not to do that.