IIRC NEMP is assumed to be at 50kV/m for milspec certification purposes. However most exposed devices are much simpler than quadcopters. There are some class exemptions too, e.g. electronic sights are allowed a fraction of second blackout after upset. Not something that would work for an attack drone though.

What I think makes Leonidas more efficient is they likely operate in continuous wave bursts rather than pulses. Probably with a broad comb rather than one specific value too.