You can make comparisons between Wano and many other arcs.
For example: Enies Lobby and Thriller Bark.
There is no line of Zoro saying he will kill Orochi or anything.
I'm going to take a guess and say that you're most likely thinking of what was said in chapter 950.
Where Zoro says he can't forgive Orochi and that he will avenge Yasu's death.
You probably jumped to the assumption that he will avenge Yasu's death *by killing Orochi*.
One of the candidates who can kill Orochi is on that page, and it's not Zoro...
Hiyori literally says that she "wishes [she] could kill him [herself]."
But somehow it's Zoro that wants to kill him, lol.
What you're missing are moments like when Shinobu explains that defeating Orochi means nothing and the scabbards telling Orochi that they have no time to waste on the likes of him.
That's why Zoro planned on going after Kaido the entire time on Onigashima.
Fighting Orochi was never even a thought.
Think about it, if the scabbards don't even consider Orochi as someone they can spend time on.
Why would Zoro consider Orochi in that way?
A line of Zoro declaring he'll kill Kaido? Easy.
Slice into pieces ≠ give a cut
Slice into pieces = kill, slay, or defeat
Habakiri belongs to Momo, correct.
Can Momo kill Orochi? Definitiely.
He's candidate number two for who will slay Orochi.
Momo has been training since we arrived in Wano.
When he was asked if he was ready to wield Habakiri, he answered no.
However, now that we're in the war, he might muster the courage to finally accept his sword.
Power is not an issue.
Orochi is portrayed as a joke and as trash.
His power comes from those who protect him.