Getting back to messing about with the Pimax, With PiPlay 1.2.57 (International) and the OC Plugin. My experience is that the OC Plugin is great at getting PiPlay to find the headset. I launch Piplay, then the OC Plugin. Click reset, and seconds later the GUI registers the headset. Magic!
After that getting into the SteamVR demo room is as easy as clicking "SteamVR" in the GUI. Give it 30 seconds and it loads up and head tracking works, as does audio. The problem I have is that for ages it said to press Y on my xbox controller. But it never worked, turns out that the "play and change kit" is charge only. You need the MSFT Wireless adapter for PC to get the controller to show up as an actual controller.
I know it's working, as the headset and the controller light up green in the SteamVR status notification window. That and pressing The green A button gives an audio tone. It has also Corrupted/written over the text box that says to press Y, with text that says that when I install games they will appear there. Having watched somebody launch SkyrimVR it appears that VR games will appear in the center column.
Then I got bored of messing about with that and bought VorpX, which works with Skyrim and the special edition, without needing to use an odd controller, or anything else. It is a modded game, (SE) It will even work to an extent with ENB, though it says it won't.
I do have issues with the display, though hopefully that will be fixed by downloading a profile as I hacked about with it on my own to some effect, but in a very unstructured manner. Though it does work as advertised. I'm using xpadder as a controller so I had full mouse and keyboard support via an old Xbox Controller S which has more addressable buttons in a usable manner than anything else I've ever found in years of looking.
The 3D effect was limited IMO, and it didn't help that I spawned outside in a fort courtyard in the dark in a snowstorm. Though the next morning my heart sang a little when I emerged in a blue sky over white snow. It looked right. Though I guess it needs to be calibrated. Luckily I have the example of SkyrimVR as to how to do this.