Yondu Undonta is autistic.
Or at least I could see him being autistic.
While he whistles to summon his weapon, I could see whistling being a form of stimming. He also loves to collect things. Cute things. He also has problems with talking to people and hides his emotions.
Autistic Blue Space Dad for the win
I’ve noticed, every time he has one of his trinkets to hand, he’s fidgeting with it. (As a user of fidget toys myself…)