The USSR in the early years had targeted food shortages in Ukraine and the Caucuses to starve the population into submission

This is a false anticommunist narrative created by western imperialists to boost anticommunism and Russophobia. Plenty of people in Southern Russia died during the 1930s famine, and there is no document proving anything remotely close to your claim of “starving people into submission”.

There was later a union wide food shortage because Stalin increased the export of wheat without adequately increasing production

Production was attempted to increase, and achieved subsequently, it simply lagged behind for a few years because, you know, it was the first ever successful experiment of land collectivization in human history, and there were unexpected difficulties that weren’t properly addressed with policy at the time. It’s easy to judge in hindsight, but the authorities really did everything they could to minimize the famine.

As for grain exports, these weren’t a capricious ideological decision, they were forced by the threat of external invasion. The USSR in 1929 was a preindustrial feudal shithole, conditions inherited from the Tsarist Empire. 80% of people were peasants, and life expectancy was of 28 years of age. The collectivization was carried out in a very rapid fashion in order to pursue rapid industrialization, again not out of ideological reasons. There was big debate in the CPSU against rapid collectivization, but the threat of external invasion (evidenced by the invasion by USA, Britain, France and many more countries during the Russian Civil War for the unforgivable sin of being communists) eventually triumphed and rapid industrialization was pursued.

Rapid industrialization, which necessitated rapid collectivization in order to relieve labour from the fields and move it to industry, was the key measure that allowed for the defense of the USSR 10 years later against Nazism. After yearly growths of 15% in GDP, the USSR industrialized just enough to defeat Nazism, at the horrendous cost of 25 million Soviet lives at fascist hands. Had the USSR not pursued rapid industrialization (only enabled by export of grains, the only product the USSR could offer at the time to international markets given its low level of development), Eastern Europe would have been genocided on an unimaginable scale, and Nazism wouldn’t have been defeated in Europe. Tens of millions of lives would have been lost to Nazi extermination.

Furthermore, the rapid industrialization boosted the economic capabilities of the country massively, allowing for universal healthcare, the elimination of hunger forever in the region, and therefore the more than doubling of life expectancy between 1929, when industrialization was kickstarted, to 1955 when Stalin died. People went from having a life expectancy of 28 years to above 60 in this timeframe. This, again, saved tens of millions of lives by any demographic measure you use. For comparison, Brazil went from 40 years of life expectancy to slightly above 50 in that timeframe.