Some things appear in this world, like gyroscopes (which are components for his boomerangs, since they have AMP installed), spark plugs and circuit boards (those things are easy to make, i did it before in shop class) but some stuff like crystals and Dark Matter are canon-specific. So when he actually manages to make some tech out of it, they will be poor imitations of what canon has-- the main problems he would face would be a) finding proper power sources because I imagine even little things like Grav-Con units need a lot of energy, and b) materials that can actually handle being used to defy physics without breaking down.

In he could make something like weaker versions of Snow's coat emblems and mini propulsion systems in the future I guess? But manadrives, summon portals and other things that simulate magic are out of the question.