Lots of detail here including about genetic engineering that sounds the same as that described in the 2015 Nature article, which I presumed was done in the US. but it may have been, or "maybe it didn't happen at all" as this author says!
Perhaps someone like Shyaku could confirm that similar work was farmed out to labs around the world (and where). This work may be visible in their publications. It may yield some clues.
I suspect Dr. Fauci is under pressure to confirm the possibility of this virus escaping in Wuhan, to fit the political narrative. Will he be pliable?
Scientifically, it may or may not be possible to confirm this with utter certainty. Not my field