In a previous post of mine I listed a lot of things I wished were true in the current mobile OS ecosystem. In the closing notes from my previous post I said that the first step in getting this to work is find some device that can run mainline (or non-android) kernels and can easily be flashed for development.
Just a week ago I came across a blog post by Oliver Smith that talks about getting alpine linux to build for older android phones with as much open components as possible. This wasn't exactly my idea of running Debian on my phone but it might even be better.
Alpine might be the perfect base for a mobile OS since it's very minimal and doesn't assume anything about the hardware you run it on. My only contact with Alpine before this is using it for Linux containers and for Raspberry Pi images.
So far most devices ported to run postmarketOS run a kernel from LineageOS with some different kernel configuration options, meaning they run a 3.4 or 3.10 kernel depending on the device. Some other devices are almost functional with a mainline "Blessed by Linus Torvals himself" linux 4.11 kernel.
I've tried running non-android stuff on some of my devices before but never got anything to run. I've also build some hobby projects to build Linux distributions. This is the first thing I've got to work with mobile devices. So far I've been porting the LG Nexus 5 and the Nokia N900.
This isn't the perfect mobile operating system yet. But it is progress in the right direction and it provides a great base for mobile desktop environment. The thing the postmarketOS project needs right now is getting support for a wide variety of devices so the different quirks for every platform can be found (Like the changes to build images for u-boot on the n900 instead of fastboot devices).
If you want to help: