A recent review summarizes safety gaps and the regulatory context in the FDA context

Integr Food Nutr Metab 5(6):14 Shaw KA, Williams S, Patrick ME, Valencia-Prado M, Durkin MS, Howerton EM, Ladd-Acosta Christine M., Pas Elise T., Bakian Amanda V., Bartholomew Paige, Nieves-Muoz Nancy, Sidwell Kate, Alford Amy, Bilder Deborah A., DiRienzo Monica, Fitzgerald Robert T., Furnier Sarah M., Hudson Allison E., Pokoski Olivia M., Shea Lindsay, Tinker Sarah C., Warren Zachary, Zahorodny Walter, Agosto-Rosa Hilcon, Anbar Joshua, Chavez Katheleen Y., Esler Amy, Forkner Allison, Grzybowski Andrea, Agib Azza Hagel, Hallas Libby, Lopez Maya, Magaa Sandy, Nguyen Ruby H.N., Parker Jaylaan, Pierce Karen, Protho Tyra, Torres Hilda, Vanegas Sandra B., Vehorn Alison, Zhang Minyu, Andrews Jennifer, Greer Felicia, Hall-Lande Jennifer, McArthur Dedria, Mitamura Madison, Montes Angel J., Pettygrove Sydney, Shenouda Josephine, Skowyra Carolyn, Washington Anita, Maenner MJ (2025) Prevalence and early identification of autism spectrum disorder among children aged 4 and 8 years - autism and developmental disabilities monitoring network, 16 sites, United States, 2022

Research-only powders are legal to sell but are not sanctioned for you to inject, and their quality is unverified
The cost of a new vial is trivial compared to potential complications
Fibrillogenic amylin evokes islet -cell apoptosis through linked activation of a caspase cascade and JNK1