Considering that Prussia was a Crusader kingdom like Jerusalem, with one the preserve of Teutons and the other of Franks, it's hard to think of there being distinct Prussian and Jerusalemite folks, just like Dominions being considered parts of the Anglosphere for a reason. Now, it's another thing to ask if anyone has ancestors who were over there in either place and I think most people have at least one or more who either were born, lived or died among fellows on Crusade or later.

My wife's classmate said her mother was Prussian. Then there was an episode of Law & Order: Criminal Intent: