I think the obvious thing to do with one computer per planet is fix climate change before it destroys agriculture and leaves billions of people to starve. That seems like a fairly reasonable kind of an objective. You know, there are all kinds of little optimizations you could do with these things, but fundamentally the big unsolved challenges that humanity faces are climate change and resource scarcity.
My main point is that Internet technology today does not support the right of assembly, and therefore it cannot and does not support democracy. The reason is that even though we can easily form groups on Google, Facebook, you name it, we don’t know who the people on the group are.