I'm interested in finding people who are doing something truly cool but might not be getting the recognition they deserve.
P.S. Not interested in Product Hunt or Indie Hackers.
The Partnership for Public Service (linked in the article). Pointing at The Canary because I think it fits your request to a T.
“Cool” and “underrated” describe subjective judgments, not inherent properties of projects or people.
That said, there are plenty of interesting and underappreciated projects on Github, Sourceforge, Savannah, Gitlab, Bitbucket, etc. as well as sub-reddits like /r/somebodymakethis, /r/somethingimade, etc., Kickstarter, Tindie, and so on. You might also get some mileage out of exploring social media sites that are less mainstream, like various Mastodon sited or other parts of the fediverse. You'll probably find some iconoclast types there who don't share their work on the "major" sites.