And then there is also the irony punctuation which looks like this: ⸮
https://en.wikipedia.org/wiki/Irony_punctuation
But I have never seen anyone actually ever use it. In fact I only ever heard about it so rarely that I almost miswrote and was about to say that interrobang is sometimes used for indicating sarcasm. But when I looked it up I read that interrobang is for showing surprise of course!
As for your :> there was a guy that used to use it on an IRC channel that I was on. But I never understood quite what he meant by that kind of smiley. And later I looked it up and in his case I think the description I saw on Urban Dictionary fit pretty well, which said it was like a mischievous or devious smile. And I guess that also fits good for when you are sarcastic. Ever since I read that definition of :> it makes me think of this cartoon grinch smile https://meme.fandom.com/wiki/The_Grinch_Smile
I'd call whoever is responsible for such a valuable amount of 0days expert/nation state level for sure.