I have some stuff in the pipeline that I'm working on. The first part of it has already been released (MIT license), which is to allow you to use old school 3D glasses (red/cyan) in the Godot editor (and in exported games):
https://cybereality.itch.io/godot-stereo-3d-add-on-for-godot-engine
I've also started working on an add-on that will let you use 3D mice in the editor, like the Space Navigator for 6DOF camera movement. I have some other stuff planned, but I don't want to explain too much right now until I'm sure I can get it working. I'm more focused on 3D and VR, though AR would not be hard to implement if I can figure out the math.