That’s completely wrong approach. Removing the i915 causes other issues.
To select which device, add HardwareDevicePath="/dev/dri/renderD129" to Preferences.xml (with PMS stopped) if you want the nvidia on a machine where both QSV (renderD128) and Nvidia (renderD129) are available.
I would very much like the GPU selection to be based in the GUI. It’s been requested several times but not implemented. Perhaps it’s time to request it again.
You can easily lose control of power subsystems, DRM handling, encryption, or just about anything else gated through the i915.
It is very central to the CPU’s architecture.
The QSV ASIC is separate.
Prior to the CometLake (-10xxx) architecture, QSV required the i915 to function.
In the post-CometLake architectures, it’s less important but still important to PMS as it’s used by Intel’s utilities (Intel Media Driver, intel Compute Runtime) to determine other capabilities of the host CPU.