For those jumping on the peptide train, there is a good review of the state of the industry by "Dr. Mike" Isreatel. Basically, only the GLP stuff has enough literature in human trials to show both safety and effectiveness. Everything else right now is a crapshoot. And he's not only a doctor, but also a bodybuilder who is very open about his past and current steroid use, and he's a proponent of using (proven) substances (responsibly and safely) to improve physique a d performance. If they worked, he'd be taking them himself.
Not to say he isn’t a good authority on the subject, but he has a doctorate, not an MD