Occupation of Norway
The air and naval forces used against the convoys had good value. However, as I understand the situation, even the need for the Narvik ore port was offset by other contingencies that the Swedes and Germans worked out over time so that the very long and dangerous route down the coast, and across the Skaggerak wasn't as necessary.
Many of those 300,000 would have been more useful elsewhere. IF Norway were
not occupied, the RN would still accompany convoys to the Soviets, so I don't know that you can count that as a trade-off. On the whole, I'd call the heavy Heer force in Norway a mis-use of resources.
With Spain as friendly neutral and the Pyrenes as a defensive barrier, the Nazi's didn't worry much about the Allies coming across from that direction, so the commitment of occupation force for France remains as OTL. If the Germans decided to invade Spain with the goal of closing that end of the Med, then they'd have to commit an additional and substantial force to garrison the Iberian Pennisula. Personally, I think they'd need to neutralize Portugal too and either that's invading, or parking a substantial force on the border and overflights to make sure the Portuguese got the message of whose in charge.
To the point I first raised up-thread, the Germans would be committing a ton of troops, along with vehicles, airplanes, food, clothing, fuel, ammunition, etc on their already strained supply train to get those resources to those garrisons in Norway, Denmark, Netherlands, Belgium, Luxembourg, Poland, Czechoslovakia, Greece, Yugoslavia. France, back areas of Russia, Ukraine, and whoever else I left out. To be sure, some of the garrison forces would be made up from Italians and other German allies and co-belligerents, but those fellows still need basic supplies, just as German soldiers would. That's a huge number of soldiers playing the role of heavily armed policemen, rather than regular Army.
Does anyone have an accurate number of how many Germans were committed to occupation garrison work?