[gpm]

GPS is jammable, I'd assume that the base with the fancy microwave anti-air system is capable of denying it and you'd want to be capable without it anyways.

Guidance via camera has been a thing for a long time: https://en.wikipedia.org/wiki/TERCOM#DSMAC,_Digital_Scene_Ma... I don't know if it's available open source (or commercially), but I don't imagine it would take me (or any other reasonably skilled programmer) long to develop it these days. Satellite imagery is freely available from google maps if you have nothing better.

Near(ish) peer adversaries (the kind that can afford drone swarms) are definitely capable of the guidance part.

[AHOHA]

Drones can fly safely with gnss denied environments, a system we tested it was in a mine with a very narrow areas, and at a relatively high speed too, being open in the sky would be easier.