The "VIVE OpenXR Plugin" plugin package contains some OpenXR Unity features for developers to use.
2. If you are on windows, restart your computer so Git path is correctly setup in your environment variables
https://github.com/ViveSoftware/VIVE-OpenXR.git?path=com.htc.upm.vive.openxr
Note: For "Install specific version", please copy the release version from https://github.com/ViveSoftware/VIVE-OpenXR/releases, then paste the version(for example: "1.0.12") to install the specific version.