Cold labs are cold because they have inter-dimensional “links” to some VERY cold places. I can see a machined installed ON TOP of such link being able to achieve the necessary temperature.
So that is the reason for the existence of cold labs? Fine, let’s assume you can get the required temperature. You still need some high-end ( maybe even experimental ) level of technology to compress the hydrogen and a proper tank to store it.
Anyway, I think a reasonable middle ground here is for CVD machines to simply spawn with a charge or two of that magical hydrogen near them.
I can’t possibly disagree with that.
Another idea for the issue of the hydrogen could possibly be to rebalance the spawns. I have no idea how much hydrogen spawns at once ( 50 units? 20 units? ) but what if we were to cut it in half, or even into quarters, and simply increase the spawn rate? In the end, you should get around the same amount of hydrogen, or maybe even less because of the increased spawn rate, but at least this would make diamondizing stuff much less of a pray- to-RNGesus-type of deal.
You would still need to explore a couple labs to get enough hydrogen and actually find the CVD machine, so it would still be more of an endgame thing.