https://www.mediawiki.org/wiki/Help:TemplateData#Type_parameter lists values like "wiki-page-name", "wiki-file-name" and "wiki-user-name" for looking up pages, files and users, respectively.

There should be something similar for Wikidata entities (items, properties, lexemes, forms and senses). This is particularly important because the page names for Wikidata entities are unguessable identifiers like Q5 and P31.

This would not only be useful on Wikidata - any wiki which wants to fetch data from Wikidata could have a template where a parameter is the ID of a Wikidata entity, e.g. the "item" parameter on https://commons.wikimedia.org/wiki/Template:Navigation_by