Oh ok, I see. Some of these posts do claim it's magma I see. Fair enough.
Seems like shishio and monsterkaido definitely did claim it's magma.
But some of these are also just for the sake of easier expression if we're being honest. Saying "magma dragon" is simply easier than saying "dragon made by magma-esque flames" for example.
I mean they are more like I showed in the other post those 2 are not the only one by far. But yeah I think you got the point
As for the second part, I still think thats cap. Like with all statements, a statement from a character has to be put into context.
So first of all, I looked in the japanes raws to be sure. Zoro says "its like magma". He doesn't say its as hot or ferocious or whatever like magma. So for all we know he could refer to all kinds of properties here. Thats also reinforced if you compare it to Akainu the only other "magma" we saw up close, which would combust peoples clothes while just being near it, which didn't happen with zoro for example. Second, Zoro has never seen Magma in his life.
And those comments are not referring to "magma-esque dragon" in a vacuum but to some arbitrary lethality of those attacks that were never demonstrated, where is not any basis for it so they are garbanzo statements too as well clearly piggybacking of that narrative.
Just a reminder Zoro also compared Lings goofy attack to a laser, just because it was fast and he was unable to block it. While the more apt comparison would have been like a sling or even a railgun, not a laser which has neither the mass nor how the acceleration works of that attack. And zoro actually saw a laser upclose, even tho maybe his brain doesn't understand it.
This is just not a good source like many other character moments, including from the same fight