While I love the idea, I just don't see this moving forward unless any of these projects can focus on splitting up these types of projects into a solid base, driver layer, and then UI layer. Instead they are all spending a ton of engineering resources building something from scratch.
So many projects have similarly started the same way and failed instead of working towards a base that replaces AOSP first, then spinning their own UI on top. The big device manufacturers figured out a decade ago this is the right way to go, and these small projects buck that and fail instead of just focusing on the thing they ultimately intend to focus on.
Get a good base that is removed from Google, THEN do this project.