I've tried using a 4K image as a wallpaper (on Xbox One X) but the result looked pretty bad - certainly not the full resolution. Is there a limit on what Kodi can use?
Good point! I haven't. Then again, I'm circumventing Kodi's cache anyway for the sake of quality, so I'm not sure it applies. Will check.
EDIT: Nope, no luck. Still looks worse than if it was being upscaled from 1080p.
This can be closed. It's an Xbox One X GUI rendering issue and everything works fine on PC.