The description about the system in your galaxy map can give you an idea about what the system may be demanding/offering.
It's not all 100% certain though, there is some guesswork involved.
Next you also have the trade routes showing up, which kind of give you a guaranteed offer/demand for each system.
Just do a bit of research in systems and see what sort of stuff in sold/demanded in all types of economies like extraction, high tech, industrial, agricultural, etc.
I'm sure they will improve certain aspects of it still, and possibly ship upgrades for dedicated traders, who knows.