Chinese astronauts make rocket fuel and oxygen in space

This is silly, but also begs the sillier question why we aren't bioengineering plants to produce rocket fuel

Plants are self-assembling albeit inefficient photosynthesises.

On earth, where they can harvest their carbon in situ, that inefficiency outweighed by us not having to make them. Their main components by wet and dry mass, carbon and oxygen, are dissolved in atmosphere. In space, on the other hand, the major cost is lifting. (Even earth, farming quickly becomes uneconomical when just water costs balloon.)

In space you’re moving all the mass the plant is built out of at exorbitant cost. At that point, you might as well just assemble the machinery on the ground and get the efficiency boost.

I can only see an exception arising if lifting costs start scaling with volume more than mass, i.e. post chemical rocketry, at which point sending up compacted carbon and water and letting plants assemble themselves in space makes more sense than sending up panels and tiny labs. (That or you’re going somewhere with accessible carbon and/or oxygen.)