so I got my game to be quiet on my LCD steam deck by: using Proton 8.0-5 and DX11, vsync off, FPS in game limit 60, steam deck frame limit to 40 fps, and default graphics Low setting. The deck said I had about 2.5 hours at full battery. The fan lightly runs in the background but i deem it playable. (i hate playing games that ramp the fan up so loud and make the deck too hot.)

I've played a fair bit via steam deck and agree with above,set settings low and cap framerate lower should keep the fan quiet most of the time,Once you've played for a while you'll forget about the lower frame rate