If only hydrogen was easy to store and transport and didn't embrittle many metals and had decent energy density by volume. Running a B737 or A320 is fine but what about the A380 sized tanker that goes along with it? Maybe a plane shaped like the Super Guppy? Liquefied, it has 1/4th the energy per unit volume of kerosene. Where the difference might be made up is efficiency at conversion, but liquid hydrogen is a huge jump. There is some advantage in energy per unit mass, as long as the weight of the containment system can be ignored.
Best of luck to them but the same factors have been a limitation for a long time. Hydrogen storage has been the difficult part.