Any and every virtual surround sound device all end up outputting on stereo. "REAL" surround headphones are exceedingly rare, and considerably worse than any decent headphone. Why? Because real surround headphones jam many small inferior drivers into each cup, instead of two very good drivers.
Dolby Headphone, Sennheiser GSX, Creative SBX, the Mobius headtracking htrf, Windows Sonic, Dolby Atmos, etc, ALL are virtual surround that output to STEREO headphones. Those technologies are all what convert the 5.1/7.1 signal into a surround mixed into 2 channels.
The new Xbox and PS5 have similar tech built into the systems themselves, so there is no longer a need for external devices, unless you just want a different flavor of virtual surround. This is why the Penrose doesn't need to include such tech. The systems already have it.
My headphone guide revolved around the use of virtual surround for headphones.