Not long before WW II, a major deposit of nickel was discovered at Petsamo in far northern Finland.
The area was overrun by Soviet troops during the Winter War, but was returned to Finland in the 1940 treaty. (This may have been due to British pressure, as a Canadian company was engaged in developing the nickel mines.)
When the Continuation War began, German troops from Norway occupied the area, securing the mines against Soviet attack.
Thus the nickel production of these mines was available to the Axis.
I have attempted some research, but not found any answers to the following questions:
1) What was the nickel consumption of Axis industry (especially Germany) during the war?
2) How much of this nickel was obtained from the Petsamo mines?
(The WI implications are obvious: Allied control of Petsamo would deny this nickel supply to the Axis. If the Petsamo nickel represented a large proportion of Axis nickel supplies, that could have a major impact on Axis war production.)