Although water vapor is technically a "greenhouse gas", it is not responsible for forcing any global warming. That's because at the temperatures we're interested in water is a liquid, not a gas, and what small amount of water remains gaseous is entirely determined by the air's temperature. So water vapor can't force any warming, it can only amplify other forcings.

uh, no?

Well technically yes

Yes

》Water vapor is known to be Earth’s most abundant greenhouse gas

https://www.nasa.gov/topics/earth/features/vapor_warming.htm...

Run it through a condenser, feed it into a holding tank and dispose of the water at each filling station?

No need, the atmosphere is a sufficient condenser. Unless you heat the atmosphere with a lot more energy than the little bit you get from combusting the hydrogen in question... but then you'll have bigger problems as your oceans begin to evaporate.