Wikimedia Bugzilla is closed!

Most special pages which return a list of pages are able to be transcluded. e.g. {{NewPages}}

UnconnectedPages is not a subclass of IncludableSpecialPage, so {{Special:UnconnectedPages}} does not work.  Adding that superclass fixes the immediate problem and the list is shown, but the page cache will probably be a problem, especially for UnconnectedPages as it is very dynamic with bots creating new items for every unconnected page.

Creating a IncludableWikibaseQuerySpecialPage will be necessary, and will allow extension authors to take advantage of the wikibase data on clients without knowing all the caching voodoo.