While i was looking on wikipedia what dukedom the newborn might get i saw a mentioning of him as prince Julian and Duke of Halland. It seems that it was officially confirmed on sunday in a special meeting of the council of state.

Prince Julian is the first of the King's grandchildren born without the HRH as he is in line of succession and part of the Royal Family but not part of the Royal House. His older brothers and the children of his aunt Madeleine lost their HRH in october 2019.

Im wondering if the choice of his name might have anything to do with his grandfather's godmother Queen Juliana of the Netherlands.