Ohh they’re cute!! I’d defo be interested.
For whether it’s been done before, I feel like there could be some similarities with Mignyans due to the eyes and teeth theme, but I think these can stand on their own just fine— you’re already off to a solid start.
For tips; I’ve found that species that keep traits relatively simple and allow lots of freedom or only have two rarities (ie dainties have regular and crossbreeds) seem to be most successful (it’s also what I enjoy most personally; in this case, not having heterochromia, the hooves, or tail type be traits with rarity would be my vote, for example, but I’d leave things like teeth ears and shaped pupils as traits). The way payment works / the cost of adopts also matters— will you take dA points and cash, or just one or the other, etc? But that comes later.