Just getting this out there for anyone checking if they can play Signal Simulator on their Steam Deck. The game is definitely playable. I've logged about 10 hrs on my Deck at this point, and here's my findings:

Proton settings: Running the game from a default preset, it runs just fine, but some of the graphics show up as green squares. Switching to the Experimental compatibility preset fixed this for me.

Resolution: 720p and 800p run great at pretty much all settings. Right now, I'm running at a forced 1080p on my dock at averaging 45-50 fps with most settings on and set to high BUT I absolutely have to have grass shadows turned off. Otherwise, I'm sitting at about 35 fps. Chromatic aberration is off out of personal preference. Texture updates can run at 20 fps, but I left it at 10 fps to save a few frames. Setting Volumetric Effects to Ultra will also be costly, so I leave it at High.

Controls: You still absolutely need mouse controls to navigate the laptop, and typing is alright with the deck keyboard. I strongly prefer only playing this with a Bluetooth Mouse/Keyboard for comfort. Otherwise, you can make the controller work out ok with assistance from the touchpads. The game will not work with a controller until you enable it for the first time via mouse controls.

Overall, it's working great and I'm chilling out to a German EDM radio station thanks to the radio feature in the game. I just needed to get the exact stream URL for it to work. Now, I just need to download some movies to my Deck to try out the TV. I'm thinking War of the Worlds, Men In Black, and some similar themed movies.