I think this is very exciting because it means that you have been able to establish a two way communication with him and that, if he learned one thing, he can learn more. And, as I found with my boy, the more they learn the tamer they become. That does not mean one can pet or cuddle them as such, but one can at least scratch them between the ears and brush their coats. Has Wally learned to come to you when tapping on the floor and calling his name? Since their vision is poor but their hearing superlative, responding to their names is key because it can be used it in all sorts of ways, in particular by singing it, which, seems to work miracles with them. Well, they are divas after all. And they love music, so that is a win-win
Have you tried giving his treat chopped in very small bits and holding them in your open palm when he sits on your lap? In that way you can lengthen the time he is in contact with you
I know it may sound crazy, but, have you tried to lie flat on the floor, so if Wally comes to you your face is level with his? I ask because that was my real breakthrough with my wild boy. Such a simple thing but it changed everything and I wished it had been the very first thing I learned about chins. In that way one becomes to them a plaything to get close to and investigate and walk over, to their natural curiosity does the job. Who knows: maybe now he is on his own you might discover a chin you did not know you had.