Yes. It will be the pre-installed default browser on Vive devices.
Unless they're referring to HTC's software suite (Viveport I think it's called), which very few people use because it's some of the worst software I've ever seen. For example, it somehow managed to jam the entire 2.4GHz and 5GHz bands in my apartment while it was running. Not even sure how it's possible to do that by accident.
I think this is actually about their freestanding arm based headsets as this is the only target Firefox Reality builds for (android probably).
For all-in-one devices, Firefox Reality will be preinstalled and the default browser.