This is a list of known Mycorrhiza wikis. Feel free to add your own to the list!
mycorrhiza.wiki: the official Mycorrhiza wiki (this website)
klava.wiki: a wiki for a Russian keyboard community
wiki.sakana.cx: an anime-themed wiki about Tsukumizu works (Girls' Last Tour, Shimeji Simulation, etc)
At least three people use Mycorrhiza Wiki for private wikis. More people have run it at least once just to see how it looks like.