She is blonde-maned and blue-pupilled and Pinkalicious actually comments on the whiteness of her... fur? Although she uses a different adjective other than white which sounds fancier and more beautiful but I can't seem to recall what is was.
Interestingly enough, the partner episode for TUF "School Rules" where Goldie follows Pinkalicious to school has this painting of a butterfly on the wall that looks a lot like the number 88... is it possible that we have a fren in the animation department?
I think it would be cool to keep track of other Aryan equine creatures who might be friends with Aryanne, and maybe if they are interesting enough some artist will draw them with Aryanne.
Swift Wind is another who comes to mind, as "Horsey" brown-furred and brown-eyed and brown-maned but the magical improvement causes white fur and blue eyes and... well the hair is another story I suppose.
The original 80s Swift Wind had 100% red hair but the new version has stripes of red+pink+blonde. I think the touch of blonde still qualifies, and red hair is still pretty white-specific, I think it's just as much associated with white people as blonde is.
New-gen Swift Wind sure looks a lot less masculine than the original one though, I wouldn't be surprised if in some future "Princesses of Power" episode they decide to make it a transgender horse. So far they still use male pronouns in both cases I think, though I've only seen the 1st season of that show.
Some close contenders would be Princess Amethyt's unicorn (white fur, albeit the mane is also white and the eyes look more gray) and I need to look into the steeds that Wonder Woman has ridden, I remember some weird all-girl team she was part of in this abandoned 90s cereal box thing but I can't seem to find it.