In electric-pump-fed engines fuel pumps are electrically powered and batteries are used as source of electricity. Yet there is another source of electrical energy which could be used in theory - fuel cells.
Fuel cells are very versatile in terms of fuels they can use (hydrogen, methane, hydrocarbons, hydrogen peroxide, hydrazine etc.). Also they are comparable (with potential to be even better) in terms of power density with batteries which are already employed electrical driven power cycles.
There is also a huge potential to increase power density of electrical motors (already satisfactory around 15-20KW/kg) from commercial ones which employ permanent magnets to cryogenic which employ high temperature superconductors. Liquid coolant is already available onboard.
Is this combination of fuel cells and electrical motors ever used in electrical pump-fed engines?