"Power a light with a lifted rock": Actually does work and you can buy this product, but it's a dimmer light for less time than the inevitable marketing diagrams indicate. Not useless but the fawning news stories over the science fair prodigy always makes this sound like an unbelievably brilliant solution rather than a rather niche hack even in the poor rural parts of the world. In the 2020s a standard solar panel, battery, and LED light are much better in every way and far more flexible.
"Provide power for a poor rural village from a kicked soccer ball": An absurdly tiny amount of power, at the cost of creating a soccer ball that is soft and doesn't move when you kick it very much, precisely because it's extracting energy from the kick and that energy isn't available to be kinetic energy. No child would ever play with this ball. Have still seen this idea at least three times now despite the fact that if the reporter spent 15 seconds with the actual ball they'd realize it's a complete non-starter.
"Science project demonstrates new way to kill $PATHOGEN": It turns out killing things in a petri dish is really easy. It means nothing about human health outcomes in a body. In fact pretty much anything about a pathogen in a petri dish - improving resistance to something, destroying resistance to something... it's really easy to do lots of things in a petri dish.
"Water from the air": Doesn't work in practice because the place this needs to be deployed to is precisely the place that doesn't have water in the air. It does work in places that have water in the air but those places also don't need super expensive condensed water when they have water already. I personally live in a place where humidity is basically 90-100% every day in spring, summer, and fall. We don't carefully capture our dehumidifier's water.
These are all things I've seen multiple times each.