The primary question is how efficient pizza is, as a food. Given it can be scaled at point of consumption and uses a large heatmass continuously, It probably is quite efficient use of flour, water, yeast, tomato paste and optional toppings most of which can be preserved passively in a cooler climate. The thermal storage of brickwork means for the investment in heating, a large number of Pizza can be cooked and during its cooling phase other dishes can use slow cooking effectively so it's doubly efficient given other potential uses: This is much the same as a bakery and traditionally Jewish bakers have used their embedded heat investment to provide slow cooking for the community on the sabbath.

So on basic economic/efficiency terms, Pizza was a good fit for a planned economy and should have been widely available. It's even moderately efficient to offer varieties, which means a degree of individual choice can be preserved and there are options to price efficiently which means rationing can be enforced sensibly.

A significant problem is that with unreliable energy supply, Pizza cannot be made but luckily, we are adaptable (homo sovieticus!) and so a large variety of things can be burned to make a pizza oven operate. Some of them do not produce good flavours and CCA treated timber should not be used for wood fired ovens routinely.

Arguably, a calzone is just a pirogi anyway. So, "yes" Lawful-neutral, Pizza was invented in Russia.