I imagine there's a "real" hyper modifier but I haven't attempted to use it. For my sake, since I use GUI Emacs I find that I have enough mappings without it (I'm also a dirty evil user). A friend makes extensive use of it because he primarily uses Emacs via a terminal and Hyper avoids all other terminal keybind conflicts he might otherwise run into. But, he uses X11, too so no PGTK Emacs even if/when he does run GUI Emacs.

I'll try to dig into this some though and see if I can (a) determine a way to map a "true" hyper to my keyboard and (b) use it in PGTK Emacs and follow up with you.