And beyond the autonomy, how much energy do you need to create this hydrogen-powered cells? I think in batteries there is a 10:1 in EROEI [1].

[1] https://en.wikipedia.org/wiki/Energy_return_on_investment

It's similar-ish. See https://en.wikipedia.org/wiki/Fuel_cell and https://www.powermag.com/fuel-cells-vs-batteries-whats-the-d..., tho the latter may be biased.