Yes, Tylenol #3 is otc in many countries

In all seriousness though providing drug users a route to buying drugs that were safely and reliably manufactured would both significantly lower harm and significantly limit the impact of cartels (see how they switched to controlling avocado trades as they are now losing the ultra lucrative marijuana market). Further, by not forcing users to go underground for their trade you could not connect them to resources for rehabilitation much more easily and earlier in the process of addiction

So yes you should unironically be able to buy safely manufactured heroin and cocaine and fentanyl in a store. Maybe not the grocery store, but a store