"New stuff" in the sense of entirely new components that you might put on a real ship? Some salvage drones and a salvage capture thingie. A variant docking clamp.
A bunch of stuff on jury-rigging and using substandard components that doesn't change anything about building proper ships, but allows you to play in a "I wonder what will break this week" level of shipping that isn't a thing in High Guard currently.
A bunch of stuff on using Astrogation for in system travel.
Obviously haven't played with any of this yet to see how it actually works, but it is all the kind of thing I want to work and was missing from basic Traveller, imho. Not everyone will want a flying rustbucket vibe or spend any time on in system travel instead of just jumping, but both those things are right up my alley.