There is a plugin that can do something like this. It is
TOC View Generator. The author hasn't updated it for calibre 5. But, I posted an update version at the end of the thread that should. But, I haven't tried it since then.
But, as they are produced by FFF, are you sure there isn't a way to generate this onto the information page it produces? It might be site specific what happens, but, I know some will do this.