I made the folowing graphical changes:

For Snowrunner's options:

-Display Mode: Fullscreen

-Display Resolution: 1024 x 576

-Sharpening: Off

-Effects Quality: Medium

-Texture Filtering: x2

Steam Deck's performance options:

-Per-game profile

-Disable Frame Limit

-Allow Tearing

-Half Rate Shading

-Scaling Filter: FSR, sharpness 5

Anything not mentioned was left unchanged.

For performance it gives an incredibly smooth gameplay experience, rarely ever dips down, and as long as you play on the Deck itself, the visuals aren't really discernibly different from standard Medium settings, with linear scaling and standard performance settings. I think if you used some of those screen glasses, or an external monitor, this would obviously look pretty bad compared to the stock settings, but on the tiny 800p Deck screen it looks good.

But Snowrunner is also an incredibly slow paced game. If you favor graphical fidelity, I can confirm the game also plays fine, and never dips further, if you use stock Medium/Performance settings, and hard cap the FPS in game at 30. Of note, I'm talking strictly about using the in game FPS limit, using Valve's will induce input latency.

In short, use my settings if you want smoother gameplay, use the stock settings hard capped to 30 if you want better graphics.