I wrote about the privacy-preserving telemetry system in @EndlessOS and why I believe that, done right, telemetry in free software is Good, actually. It's a long article! But there's a Spiders Georg reference midway through to break it up a little.
@glyph@wjt You'll want to start with https://katzenpost.mixnetworks.org/ I believe if you're interested in Mix Networks. At least, that's the best effort so far that I know about (although my knowledge might be a couple years out of date).
Happy to learn if there are other #mixnetworks I should pay attention to though!