Germany still had control of Southern Europe through Greece and Bulgaria, so noy sure how this would benefit Russia other than the usual channels via Mutmansk or the northern Pacific route.
In regards to German supplies: the Germans lost a large number of transport aircraft to Allied interception. Had these transports not been used in North Africa, they would be able to augment the numbers used historically.
Aboard those lost aircraft, were supplies: food, fuel, ammunition, uniforms, medical supplies and much more. These lost supplies would have been of great benefit on the Eastern front.
The transports themselves, consumed a large quantity of fuel, which could have been put to use for the war effort on the Eastern Front.
The transport ships lost, also carried large tonnage of supplies, including men, machines, fuel, food and more which could have been of great use in the east.
And the above does not include all the forces deployed (Luftwaffe, Wehrmacht and Kreigsmarine) along with their vast quantities of fuel, ammunition and other support.
On a typical day, the Luftwaffe was flying about 100 transport missions between Italy and Tunisia. That is a tremendous expenditure of fuel alone, just to move those transports. Fighters were also assigned escort duties for these transports, which also consumed a great deal of fuel.
The list goes on, but the point being, that had Germany not been involved in North Africa, all of these vast amounts of fuel, food, ammunition and other supplies would have been available to the invasion of the Soviet Union.
Add to that, all the fighters, transports and bombers, plus tanks, AFVs and more that were commited to North Africa, would have bolstered the German's numbers in the offense as well.