You could reward the player by allowing them to find new bodies with different abilities. Later in the game, they could come across a gnomish flying contraption that would grant them a flying speed.

And you know at some point, they could be fighting a stone golem, and the character could deliver the "killing blow" with, "I slam my hat onto the golem and attempt to gain control."

Mechanically it could work similar to a Warforged character.

Semi-related: I created a gnome subclass in this vein, gnome in a mech. Could be inspiration for anyone wanting to flesh out the mechanics of this.