The value of `sys.executable` in vtkpython does not match the actual path to the executable. This leads to errors in quite a bunch of places (mostly libraries but also some native functions from cpython). It would appear [`vtkPythonInterpreter::SetupPythonPrefix`](https://gitlab.kitware.com/vtk/vtk/-/blob/694c06111ea5a379e4b9fd8f2184259031036bd8/Utilities/PythonInterpreter/vtkPythonInterpreter.cxx#L683-714) isn't doing its job properly.. It also appears that `vtkpython` is hardcoded in the code, which doesn't work with `pvpython`. I can help provide a PR if I'm given a little bit of guidance. Thanks for your help !