Finland would switch sides very quickly, freeing up a lot of Soviet personnel.I would be satisfied with that and pretty much little need for the Allies to do much else!
The allies having far greater sea lift capacity would be more able to supply locations in the North of the country.
Norway in such a scenario would be for the German Army a self sustaining POW camp and I would suspect that even more troops and aircraft over OTL (about 1/3rd Million troops) would be sent there fearing such an allied push.
And Hitler & the Ruhr would go ape over the loss of iron ore during the winter.
Provided they could take Narvik & area fast enough. How many LCTs can be crammed full of Victors?
I don’t mean to be snarky, but I don’t understand how it’s easier for the Brits and harder for the Germans to reinforce Italy or Greece than Northern Norway.