Realistically, how prepared for WW2 would the USSR have been if it had continued NEP and its slower voluntary* collectivization drive? Without Stalin’s peacetime totalitarianism the Soviet Union would likely have had more “stable” growth and better outputs relative to inputs (the 1930’s economy was inefficient but compensated for lack of intensive growth with extensive growth), but if not for the factor of controlling investment and being able to transfer a huge portion of the country’s surplus directly into developing heavy national industry, idk if they would have had the infrastructure in time to survive Operation Barbarossa and manage a counter-offensive.

And yeah, Stalin’s purge of military command and America’s lend lease program were also huge contributors to how the Eastern Front played out. This is an “all else being equal” question.

*idk all the specifics, and there were probably plenty of appropriations in the mid-to-late 1920’s under different contexts, but it was really under Stalin that the idea of rapid, comprehensive, un-nuanced non-negotiable collectivization took hold as a national mandate.