PieFed
piefed.social
Federated, open‑source, ad‑free, and fully under your control. Build or join a community that reflects your values with no corporate overlords. This instance is run by the founder of PieFed. [Mobile apps for PieFed](https://piefed.social/post/1258559)

You’ll get taken to a random community. Once you arrive there’s a link at the top of the page to /r/random so you can just hammer away at that until you get somewhere that’s the right combo of random and interesting.

There is also /r/randnsfw that takes you to a random nsfw communty if your instance has them.