I'm saying if the OP's theoretical goal is less drug addicts in cities across America, continuing to build the wall and/or getting rid of fentanyl will probably not do much to achieve that goal. It might even have the opposite effect.
Also, considering drug addiction often goes hand in hand with mental health issues, another thing that is probably not the solution: cutting mental health and rehab programs...(as many repubs and even some democrats have done.)
If you want to ease drug addict suffering, either give them supervised exact doses of pure drugs with clean needles ...or have programs that can help the addicts who want help with their mental issues and other rehab type stuff to get them to quit........ Or both.