It’s hard to say. I have merged all changes in AOSP code and now have to go through incompatibilities in Mediatek code. Unfortunately I can only see what breaks one project at a time: I fix one project, the next project breaks, I fix that, and so on …
Edit: While I was typing this, I was building … the build succeeded without failure. Exciting. Fair warning though: If something compiles does not mean that it works …
Edit Edit: Bootloop 