The idea is simple. Because there exist heat pumps why not guess an innovation based on that. Just simply by changing the word heat to something else.
However this was not how I guessed that there should probably exist a moisture pump. I got it from learning that wood is used in a hugelkultur to capture water. Then I thought. We got water damage in a summer house a long time ago and it takes a lot of energy to dry the wood.
This makes me suspect that maybe moist wood has the ability to draw more moisture from the air. Making it harder to dry it.
If it is so. Then wood could serve as an inspiration for a moisture pump. With a moisture pump that has a higher efficiency then condensation by cooling. We could use that in agriculture or desert reversal.