EMPs are generally much harder to make than one would expect unless you plan on setting off nukes, which generally pisses everyone off.

The particular problem with organized resistance movements is the ever present monitoring of everything everywhere. This is where AI has a one up on us meat bags. When everything you do is logged and correlated the leaders of the resistance may find it hard to hide.

Simply put Ukraine is but a slight taste of the future horrors of war. Once you start mass producing things like smart mines (think something like a drone with a camera and a bomb) and just tell it to 'kill humans' your EM noise doesn't even matter, it's a stand alone unit. Things like this will just sit around a few day and catch you moving and then blow up on you.