The individual States don’t determine import rights or import duties.
Moreover, any deal the US offers the Uk will be structured to meet the objectives of US businesses, the leaders of which understand that the weak position the UK has put itself in is an opportunity to enforce terms that are very positive for US businesses regardless of the impact on the UK economy/society.
But don’t fret, this isn’t going to happen just yet, the UK must first do as it is told wrt to Ireland.