Add Opium Trade Good

[Trin Tragula]

Export and large scale production of opium was very limited in 1444. For our start date opium would exist in at most 2 provinces in the entire world. I'm 1820 it'd be around 3-4 (all of them in Malwa and Bengal).
The type of political spreading of opium to addicts that you describe also does not really fit the EU4 era.

Given that it's just not important enough to be it's own trade good in this era
It did have a very big local impact though and some regions were famous for it, which is why you'll find it in national ideas.

 

[Trin Tragula]

I swear I've seen a member of staff say opium is part of the "spice" trade good in game.

It is, but in most cases it's not significant enough to even make spice the primary trade good.
You can see in province history, as Golladan says, when spice is put in to represent opium.