Plotting 3D Backend Not Working - Mac M1

Describe the bug

I'm trying to run the mne_inverse_envelope_correlation.py example locally on my Mac M1 13 inch, 2021, but get a RuntimeError: Could not load any valid 3D backend: pyvista, mayavi, notebook.

Expected results

I would expect that the conda install pyvista would make this work?

Actual results

Traceback (most recent call last):
  File "/Users/adam2392/Documents/mne-connectivity/examples/mne_inverse_envelope_correlation.py", line 100, in <module>
    brain = stc.plot(
  File "/Users/adam2392/miniforge3/envs/mne/lib/python3.8/site-packages/mne/source_estimate.py", line 651, in plot
    brain = plot_source_estimates(
  File "<decorator-gen-153>", line 24, in plot_source_estimates
  File "/Users/adam2392/miniforge3/envs/mne/lib/python3.8/site-packages/mne/viz/_3d.py", line 1765, in plot_source_estimates
    backend = _get_3d_backend()
  File "/Users/adam2392/miniforge3/envs/mne/lib/python3.8/site-packages/mne/viz/backends/renderer.py", line 153, in _get_3d_backend
    raise RuntimeError(f'Could not load any valid 3D backend: '
RuntimeError: Could not load any valid 3D backend: pyvista, mayavi, notebook
(mne) adam2392@adams-mbp-2 mne-connectivity % pip install pyvista
Requirement already satisfied: pyvista in /Users/adam2392/miniforge3/envs/mne/lib/python3.8/site-packages (0.31.1)
Requirement already satisfied: pillow in /Users/adam2392/miniforge3/envs/mne/lib/python3.8/site-packages (from pyvista) (8.2.0)
Requirement already satisfied: numpy in /Users/adam2392/miniforge3/envs/mne/lib/python3.8/site-packages (from pyvista) (1.20.3)
Requirement already satisfied: scooby>=0.5.1 in /Users/adam2392/miniforge3/envs/mne/lib/python3.8/site-packages (from pyvista) (0.5.7)
Requirement already satisfied: imageio in /Users/adam2392/miniforge3/envs/mne/lib/python3.8/site-packages (from pyvista) (2.9.0)
Requirement already satisfied: transforms3d==0.3.1 in /Users/adam2392/miniforge3/envs/mne/lib/python3.8/site-packages (from pyvista) (0.3.1)
Requirement already satisfied: meshio<5.0,>=4.0.3 in /Users/adam2392/miniforge3/envs/mne/lib/python3.8/site-packages (from pyvista) (4.4.6)
Requirement already satisfied: vtk in /Users/adam2392/miniforge3/envs/mne/lib/python3.8/site-packages (from pyvista) (9.0.1)
Requirement already satisfied: appdirs in /Users/adam2392/miniforge3/envs/mne/lib/python3.8/site-packages (from pyvista) (1.4.4)

Additional information

>>> mne.sys_info()
Platform:      macOS-11.4-arm64-arm-64bit
Python:        3.8.10 | packaged by conda-forge | (default, May 11 2021, 06:27:18)  [Clang 11.1.0 ]
Executable:    /Users/adam2392/miniforge3/envs/mne/bin/python
CPU:           arm: 8 cores
Memory:        16.0 GB

mne:           0.23.0
numpy:         1.20.3 {blas=NO_ATLAS_INFO, lapack=lapack}
scipy:         1.6.3
matplotlib:    3.4.2 {backend=MacOSX}

sklearn:       0.24.2
numba:         Not found
nibabel:       Not found
nilearn:       Not found
dipy:          Not found
cupy:          Not found
pandas:        1.2.4
mayavi:        Not found
pyvista:       0.31.1 {OpenGL 4.1 Metal - 71.6.4 via Apple M1}
vtk:           9.0.1
PyQt5:         Not found

Run examples/mne_inverse_envelope_correlation.py on the reported macOS ARM environment and inspect stc.plot in mne/viz/_3d.py and mne/viz/backends/renderer.py. Confirm why the installed pyvista/VTK backend is rejected, with the example producing its 3D plot without the RuntimeError as the completion criterion.