I have deployed a public SSB server. The invite code is ssb.slaanesh.org:8008:@xk4cd6wxK63gUApR8efzzLKZMiy4pt7sfiVcXO85EZw=.ed25519~iTKDtfKr2tX2l/eFmhGFw0g990WjI5T2Te42R/g40D4=.

Profile of my own public SSB server

See this post for deploying your own SSB server on Arch Linux.