it seems like despite the fuel cell itself being relatively small, I just googled the weight of Toyota's hydrogen corolla racing prototype, which weighs 4210 lbs, while the toyota mirai weighs around 4400 lbs, Google bard also says Toyota is aiming to make it's hydrogen combustion corolla weigh less than 3,700 lbs as development continues.
Super interesting, I honestly think ICE development is being pushed to even more advanced levels, I think with the right infrastructure, they can certainly compete and if they take off I don't see fuel cells being favored over them.
It's crazy how despite how old the ICE technology is, these companies can still find ways to keep improving it, despite the engine being much heavier, the overall car weight is actually less than the Mirai which itself is a great feat. I'm personally optimistic about Hydrogen combustion for sure.