Embed python interpreter relative to executable

[cgtinker]

Thanks for the awesome project!
I'm trying to embed a python interpreter which is relative to the executable. It works, but I'd like to know if I'm doing this correctly as I feel like there should be a pybind function to target embedded interpreters relative to the executable.

void main() {
  // local directory path
  fs::path binaryFile = GetExecutablePath();
  fs::path binaryDir = binaryFile.parent_path();
  
  // paths which should be in pythons sys path
  std::vector<std::string> v = {
      (binaryDir / "scripts").string(),
      (binaryDir / "python" / "python3.10").string(),
      (binaryDir / "python" / "python3.10/site-packages").string(),
      (binaryDir / "python" / "python310.zip").string(),
      (binaryDir / "python" / "python3.10/lib-dynload").string(),
  };
  
  // https://docs.python.org/3/c-api/init.html#c.Py_SetPath
#ifdef _WIN32
  std::string str = absl::StrJoin(v, ";");
#else // Assume Linux or macOS
  std::string str = absl::StrJoin(v, ":");
#endif

  // convert -> widestr -> cstr
  std::wstring widestr = std::wstring(str.begin(), str.end());
  const wchar_t *widecstr = widestr.c_str();

  // Set python path before initialization
  Py_SetPath(widecstr);
  
  // Start the interpreter
  py::scoped_interpreter guard{};
  return 0;
}

Now there are a couple of points:

• the sys.executable always points to the executable file, never to the python.exe - is this intended?
• is it possible to set the sys.paths via the scoped_interpreter or is there any dedicated function?

The api advices to gather more info in the python doc. With the scoped_interpreter we can use PySys_SetArgvEx to add args to an executed script, but I didn't find an option to set the sys.paths via pybind. Probably Py_SetPath should not be used as the api is only kept for backward compatibility and everything should be done while initialising.