I know the fandom had named Valerie's ghost hunters identity "Red Huntress" (and I fucking love that name, don't get me wrong, it's rad as hell) but I had a thought about a potential other name she might have ended up with.
Specifically I'm imagining Danny giving her a hero name completely by accident.
Like, they're fighting a ghost together. It's low stakes, more just a bit of fun before they go grab a shake at the Nasty Burger or something. Neither of them are on edge or really thinking, this is basically just a quick chore they have to take care of before they can hang out. They've been joking and throwing banter back and forth, all that fun stuff.
And it's so chill and low stakes that Danny, in typical Danny fashion, isn't really thinking.
He's about to do something to show off or make a terrible pun or something and wants to make sure she's paying attention and goes to shout to her.
But uh... he uh... he forgot until he's already got the "Val" part out that she also has a secret identity and at this point watching them fight ghosts is a pass time for the people of Amity Park so they have a pretty big audience. One that includes the news.
So, now panicking, Danny tries to cover the only way he knows how:
He Puns it out.
And so, Amity Park's ghost hunting hero Valkyrie is named.
If we want to double down on Danny's "Hero identity name is just a slight change to his civilian name she could be Valkyrie Red (in place of Valerie Gray) though I think Red Valkyrie flows a little better lol