Wano wasn't supposed to be hundreds of chapter into Manga. It was supposed to be sooner.
The foundations of what fans refer to as "Breath of All Things" were laid all the way back in Alabasta. And it's not simple CoA. Zoro could hear the "breaths" of everything around him in a manner that seemed different from even CoO, and it somehow boosted his offensive capabilities, too.
This is what he said in that moment.
He momentarily tapped into whatever it was when he was close to death- standing at the gates of hades. But now, he's practically dead, or almost as good as dead.
I think this is building into him finally mastering w/e the fuck this is.