one of the Fchannel0 forks is still getting updated, and has an instance running.
link to instance, but visit only if you are completely degenerate
But it seems to be an isolated instance, as the federation appears to have been broken:
https://github.com/anomalous69/FChannel/issues/9
https://usagi.reisen/followers
more info:
https://fediverse.wiki/wiki/FChan
Thank you for the warning, looks like 4chan indeed