Where are the Daydream VR phones Google promised?

When Google announced the Daydream virtual reality platform at its 2016 I/O conference, the system was pitched as a core feature of Android Nougat, with strong support from manufacturers. Almost every major Android phone maker was supposed to be releasing a Daydream-ready phone, which would work with any Daydream-compatible mobile headset. But one year later, the platform is still niche, and a lot of these partners have been keeping quiet about their plans.
Google originally listed eight manufac