What software is the fediverse missing?
A Deviantart (or similar art and writing sharing site) clone. None of the current offerings are really suited for that. Sure you can use Mastodon to post art/fanart, but discovery of your portfolio is a crapshoot and so is the commenting system for people wanting to give feedback.
Re: Deviantart clone: There's been talks about adding ActivityPub features to MediaGoblin, which could be interesting. But I personally believe that making something new that was designed with federation from the start would be better.
That could make for a cool @bonfire extension