>>412150479
I dont have pico 4 but I imagine its the same as any hybrid. you need 
https://github.com/pushrax/OpenVR-SpaceCalibrator
&
https://store.steampowered.com/app/1009850/OVR_Advanced_Settings/ -> for playspace mover and other QoL

enable multiple drives in steamvr, connect headset and controllers, then use controller to calibrate a tracker and you are good for vrc fullbody.