All encouraging news.
Tomorrow rather than letting him peck at hard food, it might be a good idea to wet his feed down with warm water to an oatmeal consistency. I do this occasionally with my girls.
Even though it’s the same food, they go at it like it’s something special!
Other options are...
I’d try to get a few teaspoons of sugar water in him by dripping it onto his beak and letting it roll down.
Then, Can you put him in a dog crate or box with some towels or an old blanket, and put him in a warm, dim room for a few hours to rest?
He needs a dark quiet place to rest for the night. Poor guy.
Can he drink?
I’d like you to see if he can because that will determine if he can swallow. And if he can swallow it’s likely that his trachea is okay.
The “whistling” is concerning. Where is the sound coming from. His face area or...
...Not so easy to mark up a screen grab with your finger apparently.
But the alignment of his actual beak side to side and from the top looks pretty straight to me. I held a straight edge against the photo but couldn’t use it to draw. Someone at home on their computer may be able to assist...