So it’s a type of thermobaric weapon. It’s composed of magnesium hydride, which holds hydrogen more effectively than pressurized gas tanks, and it releases that hydrogen when detonated by a primer charge. It then ignites all that released hydrogen mixed with air to make a very impressive fireball.

A better name than “non-nuclear hydrogen bomb” exists, but would probably be longer and more specific. Hydride thermobaric bomb maybe.