An "EV grid" isn't actually a thing - it should refer to the electricity grid which is over a century old and practically ubiquitous.
90% of charging by EVs can be done on the existing network. Fast chargers make it more convenient but are not a new grid in itself.
Hydrogen, on the other hand, requires dedicated infrastructure to support 100% of fuelling requirements. Not just the stations, but the generation, storage and shipping.