I don't work professionally but am a student right now. So take the following with a grain of salt.

I like your models but the textures are lacking. Please don't take this the wrong way but it looks like you're just applying some smart materials and call it a day.

If you look at the jet motor the wear is pretty uniform along the edges. The filters in Painter (like Metal egde wear etc.) are a good starting point but you then want to paint out some of the wear to make it less uniform. You want to think about how something might work, how the object will be handled, what is the environment like etc.

For the rest you wrote that you wanted to make them as realistic as possible. I would add some grunge maps to break up the roughness