Brilliant story from my neighbor country who had a much harder time during the Nazi occupation than Denmark did. I had to chuckle at the sentence Norway had had enough of unwanted guests, because Denmark used to be one of the unwanted 'owners' of Norway, before Sweden won a war. There is even a SATW comic about it. Same for the use of clothes and decorations to show resistance to the Nazis, this is one of my favorite SATW comics.
A couple of name comments: I think Nils' surname would be Haaland, with a single a in land, and the teachers middle name would probably be Erik, not Eirik. Also, I know the English version of Karl/Carl is Charles, but it would feel more authentic and be more correct if Nils said Prins Carl af Danmark became their new king (Haakon VII af Norge).
Apart from the realistic depiction of the journey in the snow and the fear of discovery, I liked the way the boys grew closer until the kiss in the snow laid their feelings bare. They would not have had an easy time being together in post-war Norway, but that's another story.