The problem with this kind of initiative is that people don't agree on what positive news means. Your selection is very ideologically slanted. People on the right could interpret these news stories as negative. For example:
1. 99.7% of power capacity coming from "clean power" can be interpreted by people on the right as the grid getting more expensive and less reliable in order to solve a climate problem they don't think is real.
2. Countries committing to a global fund to protect the Amazon can be interpreted as using money critically needed at home to bribe South Americans into doing what they should already be doing themselves. If the people who actually live next to it don't care enough to protect it themselves then why should random people in Iowa or Ireland be forced to?
3. The US prison population being low is only a positive if crime is low. If people don't feel safe, then it can be interpreted as a result of not locking enough people up, and positive news would be hearing that the prison population is going up. This claim may not feel positive if you just saw the video of the murder of the Ukrainian lady on US public transport by a known-dangerous dude who just randomly stabbed her from behind for no reason.
A news feed that is only positive news for a conservative would obviously look very different to such a feed designed for liberals.