By law you have to take 30minute break after 8 hours. And you cannot drive more than 14 hours per day. Iirc Tesla semi can get 400mi from 30 minute. If they can up that figure to 600, then fuel cells range and competitive advantages diminish greatly.

But when you have near autonomous truck that runs closer to 24 hours per day or have a co driver in cab splitting duty then fuel cell will have an edge