I think weed should be okay to use and purchasable from those shops on san fierro. And also there are various locations on the map that could serve as drug factories (big smoke's crib on los santos, the warehouse on san fierro, and the mafia warehouse on las venturas) where players could sell ingredients and buy new drugs from them.
Kazutoki Kono himself bestowed me the power of all eight ace combat protagonists whenever an enemy seasparrow shows up