Wrote a quick program using their first gen product that lets you navigate the web (slide up/down, page up/down, navigate forward/back) with simple gestures. Realized the licence for the API was crazy restrictive and had to remove it from github.
Consumer headsets with head tracking were available for at least a decade before the Oculus Rift launched, at a price lower than the consumer Rift launched for. They might have had a much narrower field of view, and the tracking might not have been all that accurate, but they were working with what hardware was available at the time. The Rift being significantly better was more a result of hardware designed for other devices, like smartphones, advancing to the point where it was no longer prohibitively expensive to put in a consumer VR headset. Oculus may have certainly been noteworthy for getting people interested in VR, and showed what a consumer device making use of modern hardware could do, but they're far from the first "real" VR headset.