My money is on some type of frequency disruption for drones.
I would think a shoulder-fired flak cannon with a proximity fuse and a kill radius of about 5m would work. Anything that could take the props out would do.
I can see it now: the Warthog of drones.
I recall M1-A1 training without adding pounds of ultra-expensive equipment:
The M203 was my buddy throughout my time of service. Finding the extra weight and large grip under the barrel significantly improved rifle accuracy was icing on the cake of an all-around problem solver.
After some practice with the front elevation leaf site I didn't see a need for electronic enhancement. But too much of the modern military attempts to "dummy-proof" everything to the gleeful enrichment of contractors.
In practice, it won’t be any better than an M-79 or a 203.