The problem is there are too few socialist societies left because they’ve all failed. My parents lived through one (Poland) which had all the same shortages and pollutions. It’s the same story anywhere socialism has been tried in practice.

"Let's maybe also consider the role of e.g. US interference and sanctions in your two examples"

Or let's maybe not.

Cuba could, and did, trade with essentially every other nation on the planet, so blaming "U.S. sanctions" is not a realistic excuse for their failure.