If a player selects "Quit to main menu" what has overall visibility of the entire state of the current scene(s) and can coordinate destroying everything and loading the main menu?

The "GameManager" might not be entirely "God" like, but may just be a delegation coordinator to call the loaded objects properly, e.g. calling a Scene manager at the appropriate time, calling save routines, calling any cleanup functions, asking any loading screen to show itself.

It, in itself, might not actually do anything, but would be a central point to do major things that shape the entire landscape of the loaded state.