I am trying to add an overview map to my layout. The main map is projected while the overview map is a 'globe' (image below). I want to make the white part of the overview map transparent.
I have made the background transparent in page properties and I have turned off background for both maps. There is no option to make the background of the main QGIS window transparent.
Is there anything else I can do other than export separately and add it as an image with transparency values?
EDIT: Forgot to mention, I have looked at How to export a map with a transparent background in QGIS? but it didn't work.