Your fluffies are very horse-like, which increases the appeal with the pre-teen girls who would also like to style and play with hair.
Personally, I’d make them express thermochromatic pigments in their hair, to avoid the need for the more fragile liquid filled hollow hair tubes, but that wouldn’t change as dynamically, nor would it be as customisable.
Speaking of which, just one significant typo - thermocromatic > thermochromatic.