Why do you need an iPhone to use Apple Watch? Jeffrey explains:
All Apple would need to do is to develop an application so Watch can be setup on other devices; wirelessly, of course.
The major problem seems to be the wide variety of third party applications that run on iOS and watchOS. I counted about 18 Apple apps on my Watch and and two dozen more third party apps. Would Android app developers make apps compatible with Watch?
No. Android has perhaps 2-billion users. Apple Watch has perhaps 50-million users.