Something like Tor only solves half the problem. A Tor hidden service still has physical reality and a person who is hosting it, and who can be held responsible for failing to register the thing with the feds or file a moderation transparency report or whatever the latest nonsense is. The anonymity network helps to hide where the equipment and who the operator is, but there’s still a single point of failure and a person to blame for the community.

We need a way to run online communities that are not online services: no single point of failure, no individual or partnership describable as a service’s operator, and no meaningful way in which one person provides access to the system to another person.

You may be looking for The Promised LAN.