I don’t know anything but what I see in the news lately, which follows maybe 50 years of speculation about fuel cells. There are some fuel cells being considered Dronamics Black Swan logistics drone, and a couple of Spanish projects. One is ITP to use a hydrogen fuel cell to power a drone airship for cargo. Another proposal is with Hybrid Aerial Vehicles’ AirLander airships, a fleet is under construction for the Spanish airline Air Nostrum. These have been showing up for a couple of years in the ‘drone news’ I watch, and might or might not come along into production. I see ‘2000 watt fuel cells’ listed for a couple thousans bucks at AliExpress, AliBaba, MadeInChina dot com, eBay, and other places that might be what you’re asking about? So far, I think the problem is not with the fuel cells themselves, but it’s how to contain the hydrogen fuel safely? Hydrogen packs more energy per pound than other fuel, but safe containers are heavy and limit their usefulness. One science fiction …

Yes, batteries are much heavier. Here's a mix of stats from the first and second gen cars. 1.6Kw battery is 44kg, hydrogen tank is 87kg, it can hold 5kg of the stuff, the fuel cell is only 52kg https://media.toyota.co.uk/wp-content/uploads/sites/5/pdf/210426M-NG-Mirai-Tech-Spec.pdf https://en.wikipedia.org/wiki/Toyota_Mirai Compare this to base Model 3 battery which is 480 kg on its own

While this administration is supporting and pushing for more fossil fuel production and opening up more restricted lands for potential drilling.

Martin Seng from Switzerland displayed his fuel cell electric CH 750 during last year's Aero i Friedrichshafen. I don't have any information on the latest status.

This sounds like a problem I would assign to my students. Fun. Absent more details, I'm not really sure that it will make a difference. The combined weight of aircraft, fuel, and payload is what determines whether the aircraft will fly or not. And the landing weight (OEW + payload) is what determines how much fuel you need at takeoff. So I'm not sure I can see why it would matter whether you assign the fuel cell weight to the OEW or count it as part of the payload. But then again, I'm not an aerospace engineer.