Excellent line of thought.
I'm not a big fan of commercial drones as a delivery mechanism because drone countermeasures are improving rapidly and I suspect commercial drones are already all hacked (not to mention traceable to the owner and tracked). Most large airports have targeted and highly directional jammers (often developed by Israel) and lasers or masers. So it's probably better to experiment with a stealth delta-wing motor-glider design based on cheap, low tech models using craft techniques like this. (It's a whole lot better than printing stupid, time-wasting banners that everyone just ignores anyway!).
Using a Raspberry Pi, simple (untraceable) IC controller or stripped down burner mobile phone as the autopilot is probably the way to go (take the battery out so your movements can't be tracked). I'm sure there's literally hours of fun to be had round airport buildings, control towers and aerial and maritime navigation equipment (since they can't exactly use countermeasures near those).
Just remember to display the XR symbol boldly as a calling card so we can radicalize these puppies and get rid of the lukewarm moderates who are stifling the rebellion!
Talking of hematite, or magnetite, it can be doped onto the leading edges of a drone to greatly reduce its radar cross section. There are also many ultralight reflective materials that can be used as cheap and effective anti-laser tech. Millions of dollars of stupid, tax-draining, boondoggle military equipment can potentially be nullified with a few dollars worth of reflective material. Faraday cages can protect the tiniest of electronics. So it's worth showing the public that the state protection racket is actually a mammoth fraud.
Ultimately the KISS principle is the way to go. So the best delivery mechanisms are things like cheap Chinese lanterns, helium balloons, and hot air balloons launched upwind of the target. A tilt switch (or homemade mercury switch) can be used as the trigger for an incendiary or other payload designed to activate when the balloon lands.
But considering the lifting potential of balloons, it's hard not to dream of a HEMP device that liberates us all from this global wage-slave, tech-dystopia once and for all.
Homemade rockets and mortars have about a 50% success ratio when used against the best Israeli countermeasures, so they should not be overlooked. Remember that it costs the state millions to operate these high tech defenses#Cost), so it is a way of waging effective economic warfare (so long as the rockets are ultra-cheap compared to the defense systems).
Getting back to the OP, I think there is huge potential to be had with variations along the theme of a graphite bomb. I haven't really looked into it, but I wondered what would happen if one used a cheap mortar or rocket to launch a payload of conductive magnetic tape (old cassette tape), thin wire, or various types of graphite (powder or filaments) into a high tension power lines in a remote rural area (maybe with a timer). I'm not sure what the minimum payload would be in order to short circuit a large transmission line, but I'm pretty sure it would be morally justified based on your estimate of the GHG lethality index.
If XR wants to "raise awareness" about the fragility of our current system, compassionately donating a night or two of total darkness and lack of hot water to the public should give the average person enough time to mull it over. If the state can't even give power reliably then people will stop believing in eco-genocidal Greed New Deals and other hoaxes perpetrated by Big Oil and their investors.
Since we are under a banker occupation, I think Churchill's words when he tasked Hugh Dalton with forming SOE apply to us today (only a thousand times more so).
Ultimately the actual devices are the easy part. The tactics of financing, building, deploying and evading capture are the difficult parts.
How about this? Does anyone want to try a harmless little exercise? It would be a dry run as a Proof to concept. An XR circle gets together and divides into four teams (anonymously firewalled off from each other with Chinese walls). Team A does the research and openly publishes the plan (including strategic intel, schematics, detailed instructions, software etc.) in the clear on the web (on places like Github and Reddit) and raises money for the others. The money is left in geocaches or dead drops (with coded instructions or links to find them shared through a loose trust network) for Team B to retrieve (anonymously). Team B finds the money, smurfs the raw materials for the op, builds the devices and leaves them in dead drops for Team C. Team C are #500LoneWolves that pick up the device and do the op in secret as solo individuals. Team D mops up, provides evasion, cover, cleanup/anti-forensics, runs interference, does publicity/propaganda/media and provides material comfort, medical and other support (including co-intel) for the other teams.
My suggestion for the first op (Let's call it "Operation They Live"):
can you get those foil emergency/rescue/"space" blankets?
One of those between two blankets and you'll probably be sweating.