packaging issues with pipx, usage of sys.executable -m

`pipx` creates virtualenvs by calling out to the terminal using: `run([DEFAULT_PYTHON, "-m", "venv", "--clear", self.root])`. where `DEFAULT_PYTHON` is `sys.executable`.

Is it possible to call out to or expose the embedded python within `PyOxidizer`?

My top level CLI is `pipx` but I imagine maybe I can expose the underlying python as `pipx python`? In which case I can just change my `DEFAULT_PYTHON` and things can work as is?

I know that it's also possible to create virtualenvs with `import venv; venv.create('.venv')` but that would be a lot of code to rewrite.

Start by tracing PyOxidizer's embedded-Python and top-level CLI entry points, then compare them with pipx's DEFAULT_PYTHON and its sys.executable -m venv invocation. Done means there is a clear, supported way for pipx to invoke the embedded Python, or the issue is narrowed to the required integration and documented constraints.

Written by the indexing model from the issue text.