But then you are practically going into ASB. How on earth do you justify a conquest of the USSR by 1942 (which already is virtually impossible) while also saying the Germans suffer far fewer losses than OTL?
If you are just saying "could Germany while getting resources from the USSR and losing nothing to it beat Britain" well then yes, but that's just artificially setting things up for German success.
However if we are saying that Germany with enormous luck and everything going well beats the Soviets more realistically- with enormous losses- things are very different.
1. Back to your original post. The resources and labor and factories in east will NOT be "free". Have you forgotten scorched earth? There will be no factories, "labor" would be unwilling and hateful slaves, there would be literally millions of partisans fighting back against genocide, and Germany would likely get very, very little resources with almost everything sabotaged and then re-sabotaged continuously by the partisans. Just like OTL, the conquests might be enough to kick the can of lacking resources down the road, but just that. Germany will never, ever be able to fix its resource problems.
2. The cost of maintaining an occupation in the East might be greater than the cost of fighting the USSR's conventional army OTL was, and certainly at the very least equal to it. As previously stated millions of partisans will be resisting, and since Germany is Germany they will also have to expend massive manpower to carry out Generalplan Ost and commit systemic genocide. So, in such a scenario, Germany really doesn't have any more manpower than OTL to throw at Britain. And even if it did, it doesn't necessarily improve things since logistics were always the bigger German problem and larger forces mean more complicated logistics.
3. They still lose in Africa. There is nothing in such a scenario to prevent that, ultimately Africa was never about mass (and indeed even in this scenario based on point 2 Rommel won't be getting very many more forces) it was about the fact that the Allies had total sea domination and the DAK simply couldn't receive enough supplies via the Med. In fact a larger DAK means even worse supply issues so won't improve things.
4. America was always in the war. Official declarations are irrelevant, even from 1939 America sent significant, massive lend-lease to the UK. Of course, if they don't declare war on Germany and vice versa, the British won't get American manpower. But for the air and sea war, this is not really an issue. Germany still loses in the air and in the seas, just later than OTL.
5. Thus Sea Lion is just as impossible as OTL if not more so.