FateDevilAce
As far as I understood(anime), only seawater was a weakness for fruit consumers, since seawater contains energy / Sea Stone particles🤔
Honestly, I rather prefer for devil fruits to appear at random all over the world after the death of their previous user, and also not instantly, etc. Otherwise, they are ridiculously easy to farm. The world gov. most likely knows about this. Doffy as well, and all the Black Market people. If I were some ambitious elite, I would hunt down people with Devil Fruits, bring them to a location with fruit trees bearing fruits that are similar to the devil fruit, and then kill the captive and farm the fruit, etc.