This is really great.
It would be better if the weights were a little more realistic. A toothbrush does not weigh that much. Or, maybe you could label things like “pack of toothbrushes” to keep people guessing.
Also, there should be some indication when the weights become “known”. I was still guessing for a while before I realized that I didn’t have to.
But, for a four day game jam this is a well-polished experience. Good job!