Short: I think your idea is fine! It sounds like an interesting variant on the SOUP formula. I think you should do it!
Long: In my personal opinion, I think that adding any "gameplay" beyond simply existing in the environment would be pushing the boundaries of the traditional SOUP formula, but SOUP-inspired ideas like yours are still acceptable for this jam! As long as your game is clearly inspired by SOUP it should be fine.
Thanks for your interest!