So, maybe final update since I definitely see a big change in Cloudy.
He definitely seems a lot more interested in different toys, even if he doesn't play with them all at once. First, he kind of stuck to one shredding toy, then started playing with some others, and now he's biting the dry grass one in the back, and he's usually moving from perch to perch, never sticks to just one (unless he's just chilling or preening, which he likes to do on the highest one now). And even when he hops onto my desk, he doesn't just eat millet now, he's starting to interact with random things he could get close to (he doesn't dare cross the other side since my laptop and hands block the way).