No, they haven't. You've summed up almost everything we know about the silhouette in your question - that Kevin Fiege has said that the Quantum Realm a nod towards the kind of thing we might see in the upcoming Doctor Strange film, and that Ant Man-Man director Peyton Reed has said that the silhoutte is intentional and nothing more.
Fan speculation says that the figure is either The Wasp, or maybe one of the cosmic entities such as Infinity or Eternity.
I'll keep on looking, but for now I don't think that anyone has said anything more.