“This is not pure idealism along the lines of Berkeley or Kastrup where mind is all there is... Reality is instead a single thing from which both mind and matter emerge. In neutral monism, mind and matter are composed of this neutral substance. It creates the two distinct realities”.

I think you (or Atmanspacher) may be splitting hairs here. If this neutral substance is pure consciousness, then that is not seriously different from what Berkeley and Kastrup mean by 'mind'.