I don't think Zoro's main fight is inside the dome. He'll probably spend most of his time here travelling and collecting heals from Marco, Chopper, Hiyori, and the Nurse Minks if they're here.
He won't be fully healed, but it'll be enough for him to go back to the roof and finish his role there, which is opening Kaido's old wound and truly bringing him to his knees for a moment.
I think the rest of the SHs will also end up on the roof as well to witness Kaido's defeat, but mostly as spectators.