I'm starting to think of Armament Haki as a continuous range.
We've seen it as Level 1 is surface hardening, Level 2 is basic emission/aura engulfing, and Level 3 is internal destruction/cuff-destructing Haki. So Level 3 is basically like a Haki Kamehameha blast. Hyogoro could be seen as Level 2, and Rooftop Luffy as Level 3. But maybe it's not so binary as Level 2/Level 3. Maybe it's a range... Hyogoro could do like 2.3, while Sanji 2.5, etc... The stronger your Haki, the further away the blast. If it's strong enough it can penetrate though entire objects.
For example this is
mostly Level 1, but it's more like 1.2 or 1.3 since we can see the start of "flow"
This can be a solid Level 2
while this can be like 2.2 or 2.3, with a bit of internal destruction.
Because if Sanji is Level 3/ACoA just like Luffy and he has ACoC on top, this dude is basically like Admiral level at least already, and that makes no sense.