Hihi super fun and cute! First off, adding to the chorus of hair as a suggestion! IDK how in-depth you would want to go, but even if you're leaning away from doing full human-like heads of hair, I think a lot of people would love a forehead tuft. Secondly: it's hard for me to gauge how easy/difficult this would be to add, but my suggestion in this kind of thing will always be asymmetry (for example, being able to pick separate colors for each ear).
Sincerely, someone who loves character creator games but whose fursonas are all asymmetrical qwq
Anyway, great work!
Edit: OMG just clicked through the animations and I ADORE that they run on all fours!