So what you are suggesting seems to be, rewrite android_native_app_glue.c in (say) Zig and compile to the .so? Good, but it would nice to see a proof of concept. Also to see how extensive the work has to be: I am not checking all the tree, but android_native_app_glue has includes itself:

  #include <android/configuration.h>
  #include <android/looper.h>
  #include <android/native_activity.h>