Saying non credible af here, but in theory one could add a upwards facing shotgun shells on top of the helmet, triggered by a Camera/proximity sensor if it detects a drone/falling grande.
Maybe add a gyroscope to check if the helmet is actually facing upwards before triggering.
All in all unit cost could be below 250$
Drone dropped munitions rarely land directly on a soldiers head; rather they land nearby and injure surrounding soldiers with the blast/fragmentation. Without some sort of active aim, this thing will almost never hit, if it even triggers.
Let's kick it up a notch and get Raytheon working on a helmet-mounted Phalanx that fires .22LR. The old farts at the trap & skeet range are gonna be in for a surprise when I show up with that bad boy.
Why not just have a drone detection and alert system, integrate it with the new HUD they're working on to point to it, and have the soldier shoot the demon bird himself?
Might want to get automatic shotguns like the AA-12 out there to desperately pepper the bastards.