I had Cyberpunk on my Steam Deck when I put it to sleep a couple days ago. I turned it on today, having totally forgot I was in game. I stared at a nightclub on my screen, dumbfounded, as I was expecting the main menu.
I hadn’t even paused the game when I put my Deck to sleep. I just hit the power button and could play instantly. I still had 30% charge from having played earlier because I didn’t even plug the thing in.
What a total shock.
Shouldn’t really be surprising though as a sleep mode should use minimal power. PS Vita and switch sleep mode also tend to last a very long time