What you get on a Wiktionary page is a description of words in several languages with that particular spelling. Of course 1 spelling can also be several words in 1 language already.
It's at the level of the definition that one can link to the current Wikidata. Provided Wikidata wants to have entries for all those definitions. I'm not very active in Wiktionary anymore, but a template pointing to wikidata might make sense on the Wiktionary page.
Of course you'd prefer to link in the other direction. I guess a separate wikibase with links to WD would be better. Can those query languages query across more than 1 wikibase?