An easy modified Desktop Environment written in Python was one of the goals of the "One Laptop per Child" project. They succeeded[1], it's now separate from the hardware and can run on anything from your phone, raspberry pi, regular computer and the OLPC-machines.

(Another goal was better sandboxing bitween apps. Their project was called Bitfrost and was in many ways the first step towards flatpak that we use today)

[1]: https://www.sugarlabs.org/