I mean like in PS CS6, where you hit F a couple times and there's nothing on the screen but the photo and any background resulting from photo being scaled down or aspect ratio. I have not seen anything to indicate that this is possible in LR, yet one thinks it would be.
How about hiding the toolbar, side panels, film strip, module chooser, filter bar and hitting "L" twice? It might not be identical to Photoshop but it's close.
Edit: typo correction