Deep Pause is a new plugin being developed that will bring true quick resume features to the Steam Deck.

Plugin is in development, not fully ready yet.

There’s also the plugin “pause games” that can suspend a game, stopping it from having any CPU/GPU load while you play something else. However it doesn’t free up used memory, and sometimes controls don’t work when multiple games are open, with one game intercepting inputs meant for the other games. So this would be pretty cool if it works out.