LRAD does not use microwaves. It is strictly sonic, which can’t blister someone.
However, MEDUSA (Mob Excess Deterrent Using Silent Audio) is a technology that doe use microwaves to create popping sounds in the head for sound communication:
https://www.wired.com/2008/07/the-microwave-s/
More here:
https://www.newscientist.com/article/dn14250-microwave-ray-gun-controls-crowds-with-noise/
Back when flash cubes were a thing, some people would hang one on their belt on military flight lines. They’d go off if you were taking a good dose of RF energy. Not sure how you could do it on the cheap, these days. Small fluorescent bulb, maybe.
Gee, what do they call the square black thingie? The emitter, or perhaps projector?
What’s it made of?
What if someone threw a rock at it, like some kid who has a good fastball.
How about a ball bearing from a slingshot?
Or an arrow from a compound bow set at 60# or so...
Couple of rounds from a .303 Enfield?
How about a couple of Molotov cocktails?
Hypothetically.