They could also have considered porting Minix 3 OS - https://en.wikipedia.org/wiki/Minix_3 https://en.wikipedia.org/wiki/Minix_3 - to the mobile platform. It is

They could also have considered porting Minix 3 OS - https://en.wikipedia.org/wiki/Minix_3 https://en.wikipedia.org/wiki/Minix_3 - to the mobile platform. It is freely available with far less restrictive license than Linux. The only "production" ready and usable Linux based mobile OS currently is Sailfish OS - https://sailfishos.org/ https://sailfishos.org/ . There is also Tizen OS https://www.tizen.org/ https://www.tizen.org/ and LG's webOS - https://en.wikipedia.org/wiki/WebOS https://en.wikipedia.org/wiki/WebOS , though I don't know how how much Linux support is open to use in these two.