I made a full comment in this thread. The bottomline is

1. Sandboxing of resources both hardware (gyroscope, network devices) and data (photos, music) takes a lot of trial and error.
2. There is a need for an ecosystem: i.e. apps sould be able to create calendar events, or access shared mediaplayer — also with permissions
3. Developers need to adapt to the software ecosystem
4. Hardware companies e.g. smart watch, projectors, TV need to adapt

It all takes years.

Linux phones are around for enthusiasts since Nokia N900 (which was/is a masterpiece) — yet nothing is remotely close to a mainstream phone.