Not sure about Hayate vocals yet tho...haven't heard much
His vocals were rough in the last episode. During rehearsals at least. He missed more than a few important notes but he managed to pull through during the performance itself.
But Hayate is like a whole head shorter than the debut team, whereas Jo, Harua and Fuma are all tall. It kind of throws the whole team out of balance. They're gonna be giving him high heels if he debuts with them.
Same with little kiddos like Minhyung and Yejun. They're so tiny and small and very, very young. Both are only 15. Yejun is a literal mochi. I can't see him debuting in a group with such a man like K. He's like 10 years older.