Decriminalizing while not doing anything to discourage public use is probably the worst of both worlds. People look at Portugal like it was decriminalization alone that solved everything, but it didn't. They actively dissuade use and refer caught users to treatment.

With the backing of psychologists and other health-care professionals, the law decriminalized the use and possession of up to 10 days' worth of narcotics or other drugs for individuals' own use. (Dealers still go to jail.) Instead of facing prison time and criminal records, users who are caught by police go before a local three-person commission for the dissuasion of drug addiction, a panel typically composed of a lawyer plus some combination of a physician, psychologist, social worker or other health-care professional with expertise in drug addiction. The commission assesses whether the individual is addicted and suggests treatment as needed. Nonaddicted individuals may receive a warning or a fine. However, the commission can decide to suspend enforcement of these penalties for six months if the individual agrees to get help—an information session, motivational interview or brief intervention—targeted to his or her pattern of drug use. If that happens and the person doesn't appear before the commission again during the six-month period, the case is closed.

https://www.apa.org/monitor/2018/10/portugal-opioid