How to create complex 3D interfaces from umaps

Hi! For my space game I built a 3D starmap with its own system and planet actors, camera pawn, lighting, post processing, etc. and saved it as a umap.

Now I would like to display this map ingame when I bring up the pause menu. I wonder how to do this because I cannot just unload my main level. When I load it via streaming the light settings will get mixed up. Also, where to place the level (in front of the camera) and how to integrate it into the UI. Then, there is also the problem of pausing the main game but allow ticking and input in the loaded level.

Any thoughts on this?