Comment by QuantumGood

You can get some branded prescription pharmaceuticals in the U.S. from outside the U.S. via workarounds (1), and find heavily tested peptides via (2), in both cases avoiding the worst of the black or gray markets. If peptides, it's worth passing the hurdles and tests to access resources at https://pep-pedia.org/

(1) Start by filtering for Brand (not generic) and then going though lowest-cost results for reliable branded manufacturing locations (e.g. Germany, New Zealand, Singapore, NOT India) at https://www.pharmacychecker.com/ . Some sources are less picky about accurately checking prescriptions (e.g. https://www.inhousepharmacy.vu/ ). US Gov't allows buying outside U.S. for personal use, but reserves right to block incoming packages, but practically speaking does not.

(2) Filter for vendors with the best results at https://www.finnrick.com/about/testing-methodology