This is covered in the GrimDark Future Forum, but just to clarify for the sake of Firefight, Drones taken as upgrades (e.g. Grunt option B Gun Drone) simply count as an extra weapon that can be fired for the Grunt right? And it still uses the Good Shot rule?
Drones are just regular equipment upgrades, so are treated like any other upgrade. I think the big confusion comes from the fact that people tend to use separate drone miniatures from their regular miniatures. For all intents and purposes in GF you can just put the drone on the same base as the model upgrading with it.
My confusion comes from the listing of Gun Drone  as an available infantry selection. Attaching them to the base makes sense to keep the drones that are able to fight and move on their own separate from the drones that are simply upgrades for the Grunts or Battlesuits.