The ones you can install will either only blur the full image, or only the foreground.
EDIT - For anyone else finding this topic having the same issue. You are out of luck. ETS2 has no depth (the shaders can only see a flat image, just like your monitor) i think this must be due to how the game's internals work. Reshades DOF shaders therefore can't ever work on this game, as theres no actual depth they can grab so it's a case of use the crappy DOF the game comes with, or have none.