@danielmcquillen The PySide2 support is provided by two Python files:
https://gitlab.kitware.com/vtk/vtk/tree/master/Wrapping/Python/vtkmodules/qt
You can copy those files into an existing VTK 8.1.2 installation in order to get PySide2 support. If that isn’t possible, you can copy QVTKRenderWindowInteractor.py into your own project and import it directly.