Usopp Eats A Devil Fruit. That doesnt necessarily mean Usopp would know how to make his weapon to eat the Devil Fruit. As interesting as that would be if would not service his character or his technical skills.
The weapon literally has a mouth in its Grown Up Kuro Kabuto state. That doesnt necessarily mean Usopp would know how to make his weapon to eat the Devil Fruit. Sabo eats aces devil fruit usopp becomes god usopp and doflamingo creates the birdcage.
Usopps Secret Devil Fruit - One Piece TheoryWill Usopps Kabuto eat a Devil Fruit.
Season 17 Episodes 678 679 and 680 Reaction. After Usopp and Sugar pass out Doflamingos evil scheme is exposed to all the citizens of Dressrosa about their loved ones who were turned into toys against their own will. The weapon literally has a mouth in its Grown Up Kuro Kabuto state. Usopp stays as a regular human great for relatability of the character imo.