我将如何为Android OS或Linux OS制作全新的GUI？

I am getting into making my own embedded system and I wanted to use an open source OS to run on it but I can't seem to find any information for making a completely customized GUI (Meaning desktop Icons, Menus, and windows). Would anyone know how to go about doing this? Or could point me into the right direction to research?I am getting into making my own embedded system