We'd be much better off if they were legalized. Users enrolled in maintenance programs don't need to commit property crimes as the drugs are provided for the pennies per dose they cost the state, they commit fewer other crimes, and are more likely to maintain housing and employment. ODs are also primarily from unknown dosages of unknown fent analogs.

A large portion of the harm you're attributing to those substances arises because of prohibition. While there's certainly substantial intrinsic harms, these are maximized by keeping them illegal, and a properly regulated system of legalization would minimize them in addition to eliminating all the harm caused exclusively by prohibition (like property crime for drug money).

For these substances, it's a complete strawman to think legalization means OTC sales on every corner, nobody serious is proposing that model, but it does mean a system of being able to acquire them in a medicalized setting.