I'd like to know the technical difficulty in porting Android to x86 architecture. Since its source is open, what is the main difficulty in getting to run on x86? Or is it correct to ask why it cannot be compiled to a Java bytecode to run on a JVM on a PC? Is it because of the Dalvik VM? I'd appreciate if somebody could explain this. Thank you.

Android does not run in a JVM. The Android Kernel is a modified Linux Kernel and written in C. You can't compile it to run in a JVM.