What do you think would be the most worthwhile one?
Determine and sort the most significant causes of harm to life on earth, including citations and with ranking corrections possible as further evidence becomes known.
Where possible, provide the ability to perform regional geographic analysis, and associate man-made causes with their financial supporters and benefactors.
Publish and disseminate this information with high integrity and authenticity assurance and without any editorial comment, ideological leaning, advertising or emotional appeals.
Tediously and meticulously continue to accept corrections and updates, and publish them in an append-only format.
(this would be something like a funnel to combine conent from academia, the press, financial transparency initiatives, and fact-checkers - distilled, open, and with community curation)
People aren't all rational, and some people (sociopaths for example, or people with vested interests who are genuinely unaware of the harm their financial investments cause) don't really care for the outcomes of those they affect.
So this platform would not immediately result in utopia - those people would be the most likely to attack it, deride it, claim that it is flawed, discredit or downplay it, etc.
Over time however it would continue its' seemingly boring, methodical analysis and attribution of problems, with gradually improving quality, verification and trust thanks to open publication.
At a certain point in time it would gain enough traction, credibility and community resilience to shift opinions at large. Attacks on the platform would intensify as it became a more existential threat to harmers.
The goal would be to reach a point at which significant threats to life are being removed as a result, and life could move on to solving gradually more minor and local issues.
You won't achieve that chasing someone else's goal.