I disagree about G4 releasing CoA, it is a completely different thing.
KOH is "steaming" haki due to Ryo overflow. G4 Luffy didnt even know Ryo overflow until Wano.
He is steaming for different reasons, just like he is steaming in G2.
What Zoro was using vs Lucci isnt KOH because it has no CoC, the small sparks are CoA, not the first time for them to show up.
The green smoke is the new standard of Ryo release that makes Enma satisfied. However, that is not the King of Hell.
Because, whenever King of Hell was named, DD and Oni Giri, it was both CoA+CoC at maximum release.
We can see plenty of scenes of Zoro vs King clashing with green smoke but none of that is KOH. Just Ryo overflow.
We saw a maximum of Ryo during Hiryu Kaen, it has nothing to do with KOH.
When Zoro used Final Attack against King which Showed Long CoC Trails, He changed Name of his Sword-Style to "Dragon/Serpent-Style"
While previously, even though He was using CoC, his Sword-Style's Name didn't Change
Meaning there are "Two Levels" to his CoC
Average Usage + Max Usage
And the same goes for CoA, Zoro have Average Usage and Max Usage (Green Smoke)
We know for certain that when Zoro doesn't use Max CoA Usage, He doesn't change Name of his Attacks
And We know for certain that when Zoro unleashes Max CoC, He does change Name of his Attack (Dragon-Style)
So it's simple, the Logical Conclusion is that Zoro doesn't change Name of his Attacks when using Average Amount of Haki, regardless if it's CoA or CoC, but when using Max Power, He does
No CoA + No CoC
CoA Coating + No CoC
No CoA + CoC Coating
CoA Coating + CoC Coating
In all of these Four Cases, Zoro's Attacks keep their Original Name
But
Max CoA (Green Smoke) ---> Adds "King of Hell" before Name of Attack
Max CoC (Extra Long Trails) ---> Changes "Sword-Style" to "Dragon-Style"
You can try it on King Fight, The Names still Match