Wikibase tracks the number of statements (wb-claims) and external identifiers (wb-identifiers) of an entity in the page properties. I believe at least the former would be useful for MediaInfo entities as well, but currently it doesn’t exist:

MariaDB [commonswiki_p]> SELECT DISTINCT pp_propname FROM page_props WHERE pp_propname LIKE 'wb-%';
Empty set (0.01 sec)