Just to clear up some misconceptions.
We see kidd in onigashima with kaido just before luffy gets to wano. This after the beating kaido give him.
During this time killer eats the smile.
But when luffy reaches wano kamazou already has a poster meaning killer has been doing tasks for orochi for a while to get that.
So no he hasnt been tortured in udon at all. The bandages were just asthetics.
All hes done is eaten a smile.