Ballard took over the UK company that had the best small fuel cells and some military contracts. They have a group dealing just with military for recharging all in field electronics from H2 fuel cell not battery packs.
DOD uses fuel cells for a lot more than drones - Automated guided vessels in the ocean for instance.
The automated refueling research that is ongoing is vital for some of these applications.
By drones he means all sorts of autonomous vehicles - we already have many in production use at BMW and I think Mercedes factories.
The workhorse collaboration was supposed to include refuelling their dragonfly last mile delivery vehicle but their finances seems to have stopped a lot of work.