Basically, I want to a mobile OS, that can be used to learn about the creation of mobile operating systems. I'd prefer one thats based on Android.
Something like Minix for desktop: A clean and small OS perfect to use in didact's examples and things like that. I know that I can use any linux/unix version (even Minix) and put it in a mobile device, but I believe that mobile devices has some specificities that needs special treatment and it will be good to know a specific system to deal with this.
I'm trying to avoid Cyanogen or systems with some "commercial purpose" (huge systems with many users and many specifics) .