Weed and opiates is a magical combo. And actually a safe one too.
I also find nicotine greatly enhances nods. I normally have absolutely no interest in nicotine, don't get the draw at all, but using one of those Juul things on oxy was like ahhhh. It always enhances a nod. Now I know why so many opiate users smoke.
Obviously though just make sure you put out your joint before you properly nod out.
If you have a tolerance to strong opiates ofc you will get nothing from codeine. With a low tolerance it is nice, but I've never had a proper nod from it. Dihydrocodeine yes but not codeine.
My girlfriend once bought a bottle of codeine (600mg codeine content) and drank a bit, decided it "isn't doing anything" after 10 minutes so downed the whole bottle. Spent the rest of the day throwing up.
Unfortunately I wasn't with her to stop her making this stupid mistake, but I was like "the fuck you doing you're lucky that was only codeine, even I can make a bottle last a few days."