Why do Eye tracking and hand tracking not work in an Unreal Engine project?

Eye tracking and hand tracking not working in an Unreal Engine project and showing "Unsupported" in Unreal Engine VRTemplate.

1. Go to Headset tab
   1. Set Hand Tracking switch to ON
2. Go to System tab
   1. Set Allow eye tracking switch to ON.

If you have a Vive console, Vive Port (or any Vive-related software) installed, try uninstalling them. Vive Port is not compatible with Varjo OpenXR runtime.

Note: Vive adds the following implicit API Layers:

Link - https://registry.khronos.org/OpenXR/specs/1.0/loader.html#implicit-vs-explicit-api-layers

Implicit API Layers have an environment variable for disabling them.

Set the following environment variables when Varjo runtime is active:

• DISABLE_XR_APILAYER_VIVE_FACIAL_TRACKING_1,
• DISABLE_XR_APILAYER_VIVE_HAND_TRACKING_1,
• DISABLE_XR_APILAYER_VIVE_SRWORKS_1

After setting these environment variables Varjo OpenXR runtime works properly again.