With Rhino for Mac WIP this guide is not valid anymore: https://developer.rhino3d.com/guides/rhinopython/creating-rhino-commands-using-python/
Instead of:
~/Library/Application Support/McNeel/Rhinoceros/MacPlugIns/PythonPlugIns/MyPlugin {my-guid}/dev
it should be:
~/Library/Application Support/McNeel/Rhinoceros/6.0/Plug-ins/PythonPlugIns/MyPlugin {my-guid}/dev
otherwise the commands doesn’t show up.