I really like this idea. Also, challenges like this might be a good way to surface existing projects which are trying to attack some broken system or problem,

I really like this idea. Also, challenges like this might be a good way to surface existing projects which are trying to attack some broken system or problem, but don't (yet) have a lot of attention or traction. Sometimes what we need is to not invent an entirely new solution, but to iterate on or fork an existing one.