Here is a patch for the "separate C executable" approach. There are a couple of small complications in order to avoid any circular dependency (either at the Makefile level, or at the _frozen_importlib / Py_Initialize level).

The proposed "-X" or BOOTSTRAP_PY approaches would be difficult, since there doesn't appear to be an easy way to generate a given file (the Python interpreter) twice in a Makefile dependency chain: the first time using the stale importlib, the second with the fresh importlib.