Hum, my split is incomplete. From a high level point of view, the initialization should be done in these steps:

1) select memory allocator, config made of C char* (bytes) and int types
2) select encodings, add wchar_t* (Unicode) strings to the config
3) compute the "path configuration" (used to initialize importlib and sys.path)
4) apply the config to Python

Step (3) should be optional. Currently, the path configuration can be set in _PyCoreConfig to avoid the need "calculate" it (operation which access the filesystem).

Technically, we may have to use wchar_t* in (1), since Windows uses wmain() which gets argv as wchar_t** (and environment variables as wchar_t* as well).