On Windows you can use ReShade and SuperDepth3D to get a SBS 3D image. I’m not aware of any other software that is still supported. I found this script which claims to allow using ReShade on Linux, don’t know if it works but might be worth a shot: GitHub - kevinlekiller/reshade-steam-proton: Easy setup and updating of ReShade on Linux for games using wine or proton.