I think we might be all overthinking this.
Chopper is a character treated like a monster, and forced to live in the icy wilderness alone, until a crazy person everyone else on the island hates shows up and makes him dream of being a pirate.
Chopper's Fruit makes him appear as a "monster", and he can create Rumble Balls to make himself larger.
I can see Chopper being inspired to make Giant-shrinking drugs, due to Gyaban x Ripley. Thank Gyaban for saving them, by making a drug that lets Giants shrink to Human size.
Caesar and Linlin are obsessed with making Giants, and Caesar, one of Chopper's science foils, is famous for experimenting on children on an arctic island.
Chopper zagging when they zigged, to make a Giant SHRINKING pill fascinates me. Would also eliminate the Giants' biggest weakness in combat: they are Giant targets.