You’re in uncharted territory at the moment – I don’t think anyone has actually tried to use a custom dataarray type in VTK with the default dispatchers yet. But the good news is that there are some CMake hooks that can help you build a version of VTK that does what you want.
Take a look at the documentation here: https://gitlab.kitware.com/vtk/vtk/blob/master/Common/Core/vtkCreateArrayDispatchArrayList.cmake
Those describe how to configure VTK to build with a custom array type in its default dispatch list. I don’t think this has been widely used, so you may run into some rough edges, but hopefully this will help you get a little farther.