enormous improvements could be made to the German resource [...] situation.
I'm not all that convinced. While tungsten is a strategic material and I had overlooked it because I was looking at the world production of 1937, "enormous improvements" to the German needs as to raw materials would be when they can acquire for cheap and securely receive the delivery of oil, foodstuffs, rubber, aluminium, phosphates, iron. Indeed it's not for nothing that the single largest item in the list is 2 million tons of iron ore. These are certainly useful, still they are under 1 sixth of the yearly imports from much closer Sweden.
As to the other items on the list; manganese or zinc are surely useful, for instance, but it's not as if Germany itself wasn't producing them. Nickel came from Finland, etc.
In short, the deal would be good, if it could be done; it would have its costs and risks; in any case it can't be called an "enormous improvement". Such a definition would be OK for the Japanese capture of the DEI rubber, or if the Germans had taken all the three oilfields in the Caucasus, or if the British had been able to rerout the Scandinavian iron to themselves.