Fuel cells don't seem to have quite gotten to practical yet, and large-scale usage last I knew is still problematic due to requiring more rare-earth metals than we actually have access to on planet Earth. Like pure electric, they seem stuck on "frustratingly close".

Even worse is that you need a continuing supply of them because of "poisoning" of the catalyst by contaminants in the fuel or oxidizer. Despite decades of research, they have reduced but not eliminated the problem. Also, if you use atmospheric oxygen as the oxidizer, it makes the problem worse since it is even harder to reduce its contaminants.