It is my firm belief that Wyll is a pre top surgery transman during the events of the games and it is one of the first things he does after dealing with the absolute crisis . Sorry his nightwear reminds me of compression gear and I cannot unsee it . He practices safe binding just to be clear , at night he just wears something to keep up the appearance so to speak + he just feels more comfortable that way . I also have the belief that Wyll is a pressure kind of sensory guy . So having that sort of weight on him helps him rest better