I’ve trying to find someway of doing this? I’ve ported from gizmos and being able to change the color/opacity of hidden lines behind existing geometry in the scene would be very useful… surely it is support?
Changing the opacity is built in but changing the color isn’t. You may have to get a little creative with something like using Render Textures and overlay cameras.
You can only change this globally at the moment. Check Project Settings → ALINE Gizmos → Opacity behind objects. Does that work for you?