In particular I have ideas for both Kitsune and Dragon MCs, but am not sure if this kind of thing can fly.
Well, of COURSE dragons can fly. They're excellent at it, in fact.
Okay, a proper answer....
Kitsune has a human form and human behavior, so it should work fine. And dragon can work too --
gorgeous YA novel Seraphina has a half-dragon protagonist and races of draconian creatures with humanoid features.
You need to think about whether your character will be relatable to the "majority audience", female teen readers. That's not hard to do, really, just develop them as an interesting character with flaws and desires. A trickster character, a love-struck Yokai, or a dragon fascinated by human culture and society.... as long as your make it relatable, it'll work. You can even add in some nice metaphorical layers if they have a fear of being "outed" or being prejudiced against.
Your audience is still teen readers though, so don't have them behave like all-knowing ancient spirits. That'll cause unnecessary distance. Your monsters will work better in YA if they're "young" by that creatures standards -- flawed, impulsive and vulnerable.
Though for the love of god, don't use metaphorical racism, sexism or homophobia and then not include actual minority characters in your story.
Also, if your character adopts a human form, it would be wise to have them match that creature's nationality (Japanese for the Kitsune, and Chinese, Japanese, or Welsh for a dragon). Definitely don't make your foreign monster character appear a white American, that's always kind of weird when it happens.