My read of the ad, as a former Flexport employee, was that they're looking for engineers who are determined and unafraid to work outside of their comfort zone.

My read of the ad, as a former Flexport employee, was that they're looking for engineers who are determined and unafraid to work outside of their comfort zone. Understanding the complexities of international customs and logistics is as difficult as you might expect. In my (probably typical) experience it is not code for long hours or anything like that. I'm not sure what "gritty" might mean more generally, though.