Presuming that Finland mantains an armed neutrality until 1943, might they join the war on the side of the allies to try and win post war brownie points, telling the Americans "Divert a bit of Lend Lease, and we will librate the north of Norway?
I would find it rather unlikely, unless it's very late in the war and Nazis decide to continue the war from Norway after German surrender. Even in 1943, if the war goes OTL like, the Nazi Germany has capability to inflict thousands of deaths on Finnish civilian population by aerial bombing.
Another option is an occupation of northernmost Norway by Finnish troops in the last days of war for Germans to avoid capture by Soviets and Finns to prevent any Soviet incursion.