In T433157#12168593, @Jdforrester-WMF wrote:

Categories are fundamentally part of wikitext, not a general thing in MediaWiki that we can plug Abstract articles (or Wikidata items or Wikifunctions functions) into. Until T112999: Let MediaWiki operate entirely without wikitext is done in some way (or at least this major part of it), there's no way we could build this into the same system.

Theoretically we could build a parallel system instead, which would likely hit the "uncanny valley" of being close but not the same, but that almost certainly wouldn't resolve your wish here.

Can’t believe I missed that. Thanks.