Technically we also had Pepsi in Romania, I drank it once or twice before 1990, but we didn’t have the consumer society the West had that made it so you could buy Pepsi or Coca Cola from basically almost everywhere.

This is one thing I've always been curious about, if you'd indulge me for a short answer. Or link!

How did consumer goods and food distribution actually happen in (commun|social)ist economies? As in, the last mile experience as a consumer?

They varied as much as anywhere, depending mostly on the level of economic development. From what I've read and from what relatives have told me, in the "good" economic years in East Germany, it was almost like in capitalist societies today. Restaurants, grocery stores, shopping malls, albeit with less selection, quality and periodic shortages and rationing of imported and more scarce supplies. Bananas were common enough but more of a "wow isn't this nice?" food you felt lucky to find in stock, rather than a daily breakfast item. Fresh tropical fruits were one of the things people were crazy for in the West when the wall fell.

Despite the reputation, the government usually was very sensitive to the issue of keeping meat or at least a lot of bread on the table. When the DDR ran out of money to import coffee in the 70s, it was one of the more serious threats to their rule and it stimulated the development of the Vietnamese coffee industry in "socialist cooperation". (Fun fact: to this day Germany is still Vietnam's largest coffee buyer.). Prices were quite low in proportion to wages, effectively government subsidised. Hence shortages, though rarely for staples. Hunger was rare after 1950. Dietary boredom was not.

In the not so good economic years, or in many parts of the Soviet Union or less wealthy socialist countries, similar story, except meat shortages and too many turnips and your wages might not afford too many restaurant visits. Out in the country there was some subsistence agriculture in the poorer places like Vietnam. Some places never Stalin-style collectivised the farms, and there you saw small market or at least barter economies in small towns and rural areas consuming local product locally, farmer's markets basically.

The actual process is essentially the same than in an industrialized country: trucks that move goods from A to B. It's just that A, B, and the agent moving the goods are very different. By "different", I mean "much worse". Maladies: bad refrigeration, multi-week delays, places crumbling down.

Check this photo of a "bodega" in Cuba (first image in this page): https://www.cibercuba.com/noticias/2018-08-01-u1-e192519-s27...

And Pepsi got a warship in return: https://www.atlasobscura.com/articles/soviet-union-pepsi-shi...

And the non-Soviet states behind the Iron curtain had Coca Cola in Tuzex and similar.