“fentanyl detection”
The war on opiates has been lost.
Opiates need to be made available to addicts in highly diluted form - two-liter bottles.
A yellow color might indicate a non-lethal to normal person concentration and a deep red color a highly-lethal except to an addict concentration.
To buy from a vendor would involve a hospital test and prescription.
I like your thinking and creative ideas but the GOP will never embrace it
Maybe some innovative state can try it. I know in Europe Portugal have basically decriminalized all drugs.