This is definitely a feasible request and I had always had plans to implement more projection types. I am not going to have time to add it in the immediate future but, if someone wanted to contribute it, the way to go about this is to add a new staticmethod on the ladybug-core Compass class, which converts from 3D coordinates to the equidistance projection. Similar to what you see here for orthographic and stereographic:
Once we have that, exposing a new projection on all of the dome-related classes (Sunpath, Radiation Dome, Sky Mask) is relatively straightforward.