What takes up RAM in android? What is cut out?

Question

Android

What takes up the most RAM in android and what can be removed from this?
The goal is to maximize the release of RAM on HDMI dongles and TV boxes for use as a server . Removing com.android.systemui and Booting Android without framework or GUI was
advised , but I don't understand much about it. And by the way, is it possible to find out which versions of android support a particular processor / chipset? And then after all, the lower the android version, the freer the RAM, as far as I know.