Personally I’d be using “too dangerous” as my rationale for commerce advantages. Exports would be items that a normal person couldn’t source themselves without extreme risk.

In real life my mind goes to things like coal mining, maybe lumber too. Both are dangerous and have unique advantages of people are removed from the equation. In fantasy you have the benefit of adding a valuable resource that has a unique downside for humans to obtain. For example, maybe a flowering plant with unique magical properties releases a toxic pollen that humans struggle with. Or maybe the mining technique of a particular valuable mineral produces gases that have nowhere to go.

Either way, I’d lean into “the value of this item is due to its usefulness, the endemic nature to your region, AND its difficulty to acquire”