Is it possible to extract the kernel and device tree from a rom? Is it possible to extract the kernel and device tree from an android 6.0 rom?
If it was that easy then we'd have custom ROMs in no time for every phone on the planet.

What's on our phone are compiled, it's basically impossible to decompile them (modern decompilers are not as powerful as you'd like to think), and sometimes illegal when dealing with proprietary components.