Could there be a chance for splitting android into two half? One for per device low level initialization and one for a shared image for all android devices?
So the idea is you be able to easily upgrade or even multiboot different android or linux images if you wish, without having to recompile for every device.
I thought mobian was distributing a GSI to do non-Android on the Android base, but I can't seem to find it if they do that.
Also, bear in mind that this almost intentionally doesn't solve some support problems - any bugs/vulnerabilities in the base layer won't get fixed by GSIs (which is why DivestOS says it explicitly doesn't ship a GSI).
Droidian is the GSI-based project from the Mobian folks. Note that GSI's are not totally unified; they'll still vary by CPU architecture, starting Android version shipped with the device, weird features like "A" or "A+B" boot, etc.
So the idea is you be able to easily upgrade or even multiboot different android or linux images if you wish, without having to recompile for every device.