Wouldn't TexTools built in tool for UV->SG work? Why would you want every face to explicitly be a different SG? Like @monster mentioned, there are only 32 smoothing groups, and you most likely will have more than 32 islands.
Why do you need seperate smoothing groups? I think most UV to smoothing groups scripts will use the same method as both of those scripts or newer scripts swill select uv edge boundaries and make them hard edges. Neither will help you. Another issue is that there are only 32 smoothing groups. I think you'll run out quickly.…