[LinuxBender]

Anything else besides hosting my own servers, and be killed by search engines?

I think you summed it up. One would have to host their own platforms and intentionally block search engines, bots, etc... In my opinion discoverability would be limited to word of mouth on chat and forum platforms until those platforms block the domain names in question and this is even assuming the platform is text-only. I assume the entry points would have to be ever changing and rotating domain names as landing points into the main site.

Any major platform that claims to support complete free speech will eventually be compelled to do otherwise in my opinion. Competing platforms, agent provocateurs and unhinged people will quickly contaminate the platform thus giving reason for governments to shut it down. One would need really good human moderators, automation, algorithms and ACL's or ranks to weed out toxicity in order to keep the platform alive which is technically a form of censorship and would not meet your requirements.