On the early days of VR a headset ran in "Extend mode" and the the OS would see the headset as a normal display. This was not efficient so vr developed "Direct mode" where the vrcompositor has direct control over the display and is not seen aa am extended display in the OS.
Some non vr programs can be played in a vr mode using SBS 3d injectors likw Tridef3d & Vortex in extend mode. Vorpex at some point also added a steam compatible "Direct Mode" in addition to the older extend mode. Pimax in the 4k combined a few different mides in pimax mode; but also kept Video Mode aka extend mode. Status of new pimax headsets having ectend mode is not known/revealed as if yet.
Kodi VR mode 4 example uses Video Mode & does not have head tracking.