Personally I think having good lighting and good material definition are the most important things to achieving photorealism. You can take it a step further by adding imperfections like finger prints, water spots, scratches, smudges, smears, dirt, etc.
Based on your photo references, you’re going to want to set up a sky light as your primary lighting source in Unreal. Many of the textures appear to be simple enough that they can be created by hand and then layered with grunge textures that are sourced online.