My sister found this site for pets that sells anime/video game theme collars (Pawsonify) and I wanted to share. This is only one of the kingdom hearts themed ones they have. :
H&F New Jewelry Kingdom Hearts Black Necklace Key Shape Chain Pendant Women Men Christmas Gift Choker Chaveiro Accessory Collar - AliExpress
Kingdom Hearts Necklace Keyblade Key Sora Riku Kair Roxas Logo Silver Color Pendant Fashion New Hot Game Jewe… | Kingdom hearts necklace, Silver color, Mens jewelry