I don't know about air travel. For comparison, Li batteries are about 200-300 Wh/kg, with solid state reading 3-4x that.
Jetfuel is 11000 Wh/kg. Hydrogen is 39000 Wh/kg.
By volume they might have an advantage but planes tend to care more about weight
I mean league still allows 3rd party skins, like the devs told the skin makers what guidelines to follow and they probably wouldn't get hit