Is everyone in this movie a cyborg?
That question is fair. The answer? Probably not.
Wookiee cyborgs are serious stuff. The conceptual artists clearly experimented with a lot of things during the creative process. One piece of concept art depicts Chewbacca with a robotic hand, implying somewhere he lost an arm during a fierce battle. Without the correct context you might think iron clawed Chewbacca is a thing in Star Wars: Episode VII. That information shouldn’t have been presented that way as all the details are needed to assess the situation as well as one can.
The truth is the piece of concept art itself has two Wookiees on it, both are Chewbacca. Against a yellow background, to the right side of the frame, the Wookiee has a robotic hand and on the left side he does not. On the left side, Chewbacca looks towards the viewer with his bowcaster slung over his shoulder, casual and cool. On the right side, he stands with his body slightly leaning to the right, indicating some heaviness from the robotic hand that has left his posture slightly off kilter. There is a note that states “Bionic arm from war wound” with an arrow pointing towards the silver arm. In both concepts he still has his classic bandolier and satchel.
After a few discussion with others, it does not appear this concept lives on in any other forms known to those with similar materials. That coupled with the lack of set reports regarding Chewbacca with a robot hand makes me think this is simply an idea thrown out there by an artist while exploring Chewbacca’s look for the film and nothing more.