He needs to reach for air differently, he has some tiny afination problems, I think less than a half tone, but it is audible. Technique is not really impressive, but that is not something you should tell hum to change, after all, the way we make music is the way our soul says to.
In the chorus, he could, after breathing, open his throat a little rounder, and try sending the voice from his stomach instead of his head, it's just a suggestion.
It's cool