In case someone needs this in the future: (this works with the above code)
polyData = vtk.vtkPolyData()
polyData = reader.GetOutput()
coordinates = []
for i in range(polyData.GetNumberOfPoints()):
coordinates.append(polyData.GetPoint(i))
will create a list of coordinates for each point
based on: https://www.vtk.org/Wiki/VTK/Examples/Cxx/PolyData/PolyDataGetPoint