Hydrogen and Oxygen Should Have Mass

Because in reality things have mass. And besides, gasses are light, so it wouldn't inconvenience you. It'd be a little QOL improvement to make the game more fun.

Actually, the oxygen and hydrogen created through electrolysis would have the same mass as the water it came from; that would make 1× inventory very interesting.

To put a number on it, 1L of uncompressed hydrogen should have a mass of approximately 44.6mg, 1L of CHG around 40g (this will vary based on compression) and 1L of LH2 around 70.8g. Oxygen will be substantially more (LOx is about 1,141g/L).

Thus a full Large Grid Hydrogen Tank (assuming pure hydrogen, not a combination), with its actual volume of approximately 270kL, would contain roughly 19.1 tonnes of liquid hydrogen. That's not an insubstantial amount, so it shouldn't just be dismissed

^ that interesting ^

Science!

If you want mass to the tanks, you are also going to consider the mass of a gas vs a liquid.

If the tanks are filled with gas, they don't last very long, but very light

Liquid filled tanks last longer, but heavier

That's kinda why I mentioned the three different masses of hydrogen in my post. Strictly speaking it's unlikely that the tanks would be filled with a 1atm gas, since that's hugely inefficient (both in terms of volume and mass, since the tank weighs roughly the same whether it holds a gas or liquid). But it's not outside the realm of possibility that their capacity could be listed as an "effective" volume by overprovisioning them (eg Instead of 270kL of CHG, it's 270ML of H2 gas which happens to be stored as CHG).

While I've personally "simulated" CHG with a mod (in terms of capacity and energy, not mass) given the general push in that direction for fuel cells, it may not be unreasonable to assume that 2077 has more ready access to LH2. NASA already uses it for the shuttle, after all (not the boosters - they're aluminium-based to help with logistics).

To put this in perspective, 270kL of liquid H2 would weigh ~19,000 Kg (19 Mg)

they do in legendary, no?

I'm currently playing it and they do not...

Ammo in Fallout 4 Survival then, that has weight.

I have never played that in survival mode xD

Ice is not that hard to find. Once you're in space you can just coast anyhow.