In the game industry, hardware manufacturers want you to buy their products and software toolmakers want you to use their software. And, with both hardware and software, their creators want you to develop games so people can play them. To be more specific, VR headset manufacturers would like to sell as many headsets as possible, so they encourage developers by providing them with free tools and assets. This is not an evil plan, rather a symbiotic relationship between hardware manufacturers and game developers.
Any look at the Unity Asset Store is a snapshot in time because of the dynamic nature of the store. At the time of writing, there were several free VR-related assets from various hardware manufacturers. This section reviews those assets.