Possibly not. AFAIK only rift sensors use some CPU (to analyse the camera images for tracking, and those are lowres so it doesn’t eat that much CPU).
The main problem with mixing HMD from one brand with controllers from other brand (with different tracking technology) is not how harder it would be on the CPU but if the software code (game code for example) has been written with such use case in mind.
Many games for example can mix up devices from different brands, like a racing wheel from brand X with pedals from brand Y, or flightstick X and rudder pedals Y.
Here it is just about mixing up other kind of devices, HMD and controllers. Typical case may be VR games/apps have been coded to hook with 1 single system (oculus or steamVR or pitool) but who knows if some game developpers may have written their code to allow to hook with multiple systems simultaneously ?
Easier way to know is to try with many games and see if it works with some. I’d expect best chance is with oculus games as pitool can run them natively (or idk how).
What happens when you launch oculus games with the pimax and also have oculus software running ?
If it doesn’t crash then check if you can use the touch with the pimax running those oculus games.