I'd love to filter the internet by "content that can give you insights right now that would otherwise take years of study in a specific discipline to even know exists".

Another that I saw recently on an HN comment (thanks tptacek) is https://www.youtube.com/watch?v=nfY0lrdXar8

A quick google for "3blue1brown awesome github" (my usual strategy for finding good similar content) landed me here: https://github.com/rossant/awesome-math

The awesome lists are pretty good starting points for finding good content, but there's a ton of them of variable quality, so you end up with stuff like this: https://github.com/jonatasbaldin/awesome-awesome-awesome (which has 68 forks...)