I managed to bring DLL from PC to Android with libs taken from Unity 2018.2.20f1 but sadly it's buggy. PC dlls are not really meant to work on Android
We have to mod il2cpp.so file (youtube.com/watch?v=S8cJr9fOS-k)
or inject il2cpp.so file (https://github.com/jbro129/Unity-Substrate-Hook-Android). There is no Il2Cpp to C# yet
I think splitted assets was because of Android ilmitaions
mystaman12, Il2Cpp is not a protection :P