I am sharing mine past experience of using non GCC spec vehicle here in UAE.
I had a Europe spec Car which provided by my company. Unfortunately I damaged the front bumper and bumper bracket. Mine insurance was agency repair so I went to Authorized Dealer workshop for the repair and the new bumper which is GCC spec is not suitable with my car. Appearance is same but the mounting points are different.
This happened because the production of Europe spec is from Slovakia and GCC spec is from Korea. So sometimes GCC spec spare parts will not suitable for other spec vehicles otherwise both should produced and assembled from same region. I heard that some American and GCC spec models are from same region, in that case I think this will not be an issue.
And also maximum temperature capacity of automobile components will be different in each spec. For example consider the maximum operation temperature of a component is 100 degree Celsius in 27 degree Celsius (ambient atmosphere temperature). When the ambient atmosphere temperature increases (in case of UAE around 47 degree) the operation temperature also tends to increase and sometimes it will exceed the maximum thermal capacity of the component and led to the failure of the component. In case of same region production I think this will be ok.
So in my humble opinion those American vehicles which produced from same GCC vehicles will be good.