There's still no evidence that WIV was doing GoF research in Wuhan. Nobody has ever come forward to say that was happening and there's no evidence that it ever happened. The simplest explanation of why nobody is defending the GoF research is that it never happened.

Researchers from WIV collaborated with UNC Chapel Hill in 2015 to do that kind of research on SARS-1-related viruses, and that happened in the US.

That gain of function experiment in mice was also to gain function in mice, it would reduce its ability to infect humans.

And if you took RaTG13 and spliced in the surface protein of SARS-1 so it bound to ACE and then ran it through mice you'd still not wind up with SARS-CoV-2. The original virus is too far distant (only 96% homology) and running it through mice would produce a virus that was poorly adapted to humans. And the spike protein would look more like SARS-CoV-1.