My suggestion is to remove optimus-manager and related packages no matter what else you do.
I still dont know if you actually need a switcher utility.
Just to be clear - the ‘hybrid mode’ of using the iGPU and calling the dGPU with prime-run is how it already works with no switcher tool.
(prime-run blender … and you launch blender with the nvidia, etc)
But if you want one … then yes, I suggest envycontrol.
Whether you use it from the command-line or one of its desktop GUI’s should not make a difference.
But yes, the basic operation of envycontrol to switch to the ‘nvidia-only’ mode would be
envycontrol -s nvidia