Add a bunch of fat, semi-desktop binaries that actually provide some kind of functionality to make it remotely comparable, and then you just have a worse, fatter system that runs hot and wastes the battery.
Android is a unified system working together to make the device race to sleep as fast as possible, with as few wakeups as feasible (e.g. batch together events that would wake up the device).
In terms of resources I think it's roughly going like this, from lighter to heavier:
SXMO < Lomiri (Ubuntu Touch) < Plasma mobile < Android < Phosh < Gnome mobile
I could also add XFCE but they officially don't support mobile.
Android isn't the lightest mobile environment by any conceivable means, maybe it's the most featured but certainly not the most optimized for low-end devices, the days of Android 11 are over.
You need 4GB of ram, a good CPU and full hardware acceleration to run modern Android.
And if the next Android bumps the requirements again, I would put it at the end of the list.