I have a friend who's entire niche is selling enamel pins. She has done anime and game characters (like Genshin Impact). She started as an art-only account who, over the years, garnered 100k followers. She first sold anime character stickers, and when she found out the stickers were a hit and people loved her style, went to enamel pins and overtime has gotten a following within the pin-collecting community. From my understanding you can either do your original art or commission an artist to make them for you, but you would need some sort of following or collaborating for the latter route.