Ski soldiers 2: Frozen Boogaloo?
its a bit of a meme but genuinely,
YES
during this time IRL in history, though not much in the southern regions of northern Europe, the very north was already used to alternative methods of travel and transport like ski's and sleighs, and most people in at least Sweden (dunno about the others) were prepared to survive war and conflict lasting 2 years without additional supplies coming in
in a setting like this it wouldnt be surprising at all to see pockets of resistance and military remnants (wink nudge) in the very northern regions being able to keep going due to being able to simply move quicker than their enemy and being more accustomed to the climate
this is short for saying please confirm there are ski soldiers and resistance pockets in the mountains of northern europe