I haven't ever wrote an Android app (just toyed around and patched a few projects, but never had an idea and a necessity to do a full one from scratch), but what's the limitation here?

Can't a native library call just anything from the Android/Java world?

I mean, NDK library has JNIEnv* pointer and it can call FindClass/GetMethodID/Call*Method. And it can create objects/functions if it needs to be called back. Of course this isn't fun in the raw form, but don't see any reason it can't be well sugared.