Pamela Anderson has been a U.S. citizen for at least twenty years.
And by the way, there are plenty of British actors who play U.S. Americans on TV and movies, but it rarely happens the other way.
For example, House, Several actors on Prodigal Son, Billions, several on Homeland, several on Walking Dead, Yellowstone, and many others. Even Idris Elba and Kate Winslet have played someone from the U.S.
Gwyneth Paltrow played a Brit in two movies, and Renee Zellweger in one movie.