WebXR Input Profiles Loader in Unity. Based on WebXR Input Profiles.
You can try the demo here.
The package is intended to be used with WebXR exporters in general, and not only with WebXR Export.
The package uses glTFast to load the models, and Unity's package of Newtonsoft Json.NET to parse the profiles.
You can get the package from 
Set a Scoped Registry in Project Settings > Package Manager for OpenUPM.
Name: OpenUPM
URL: https://package.openupm.com
Scope(s): com.de-panther
Then in Window > Package Manager selecting Packages: My Registries and the WebXR Input Profiles Loader package would be available for install.
You might need to add Shader Variants of the Input Profiles Models to the build for the shaders to work. More info about that can be found at the glTFast docs.
You can use glTFShaderVariantsURP, glTFShaderVariantsLegacyURP or glTFShaderVariantsBuiltInRP in Project Settings > Graphics > Preloaded Shaders depending on the active render pipeline.