But according to that link that was posted before, it does support 4k@30 hz input. I think that would give a better movie experience than 2k@60 hz upsampled to 4k.
I think that's going to be tough, not impossible though. Tough because basically you're communicating with the firmware in the headset, so you'd need to find out how to get it to send you the data you need. How would you do that ? I think you'd need to reverse engineer the FW, and find out that way how to get it to send you the data you need. Or, alternatively, you could maybe spy on the USB communication and find out how to do it that way. Or, reverse engineer software that does just that and rebuilt it yourself.
Either way, I think it would be MUCH easier to just use the API as supplied by Pimax. Then again, there's no documentation to the API functions and I'm not even sure which function you'd need to use to get the position data, although it can be decuded I think via the PVR_Types.h and the api itself. I've never worked on VR myself so I'm not sure which data exactly it is you're looking for but you should look at the data types in that header file and then see which functions process/retrieve that data. That's all I guess.
Look at this:
typedef struct PVR_ALIGNAS(8) pvrDisplayInfo_
and then look which function processes it:
pvrResult(getHmdDisplayInfo)(PvrHmdHandle hmdh, pvrDisplayInfo outInfo);
I'd try that first, looks like that might be what you're looking for.