Hyas Crumpp.
I may be able to dig up some of Germanys sources, such as oil and steel at some stages of the war.
In 1942 those were staggering, in 1944 very little.
BTW, the population of Germany and Italia with the conquered nations added was close to the one of USA.
And then there were the Brits with their colonies....
Anyway, this is something to look into.
Oil: Romania and the best part of the USSR wells
Food, textiles,timber, workshops, steel, Most of Euroland, and even buying from the rest.
The Brits had to cross the atlantic, or go all the way to the far east to get some of those. And until 1942, much for money...