In April South Korea based MetaVista raised the world record for the flight time of a electric friven drone by a factor of almost 6, to more than 12 hours!
This was possible only with 390 g liquid stored hydrogen (5.5 liters) and an Intelligent Energy fuel cell. For a nice video with some liquid hydrogen poured out from the cryostat see
https://www.youtube.com/watch?v=LAC8d6b0MF4
Image of MetaVista