I want to add a minimap for my VR game (Cardboard) but I want to add it as a screen overly not in the gamespace, Is that possible?
I think you should put in in gamespace, so both eyes will be rendered correctly, you can change its position to follow where the player is looking. Put it on a quad.
But it may be possible to do it like you want. Only when I created my menu gui I read that the UI components in Unity can not be used in VR.