Except for people who get incredible nausea from opiates, most people feel better on them and it's not rocket science to see why. But unless you have a terminal illness or you've tried literally everything in terms of meds, therapy, ECT, ketamine, etc. I would hope no doctor would give into this request as, even though you might be struggling now, whatever brief relief you got from opiates would quickly fade, leave you with the same or worse problems as before as well as a notoriously difficult addiction to treat and keep in remission, including all of the other fun stuff that can potentially come with opiate addiction — broken relationships, loss of job and income, homelessness, crime (prostitution, theft, b&e, armed robbery, etc.), prison, various medical issues associated with IV heroin use (which a lot of people switch to when they can't afford "clean" opiates), HIV/AIDS, hepatitis, overdose and death, as no matter how careful and smart you are, eventually you're going to get fentanyl at least once and you're not going to realize before it's too late, and then it's a roll of the dice in terms of if any of the other addicts you shoot up with care enough or are alert enough to either narcan you, call 911, or dump you at an ER or you're in an open area with enough foot traffic and you come across someone who cares enough and wants to invest the time into saving your life.

Long story less long: I personally don't think it's even remotely worth it, but I can understand the desperation and thought process driving it.