Unfortunately, Sons of the Forest is not a great experience on the Steam Deck without making some significant tweaks.
Out of the box, on Ultra Low settings Sons of the Forest will crash your Steam Deck causing a reboot after 20-30 mins of gameplay at 20-30FPS.
However, thanks to the latest Cryoutilites updates, after running the recommended settings (more info on how to run Cryotuilites here), we got a much more stable game sticking much closer to 30 FPS and no more crashes.
UPDATE: There is a bug with the V-Sync causing the FPS to be capped at 30 FPS, to fix this, change the in-game V-Sync to 30Hz and the Steam Deck performance FPS cap to 60 FPS,
we created a short showing this here