Man, I wish the sanctions would be lifted just so that the leftists holding these countries hostage, and their fellow travelers, don't have an excuse for running them into the ground because they believe in the worst ideology in history.
Cuba trades just fine with China, EU, Canada even, not even considering South America. The numbers are out there. Also countries like Venezuela were not nearly as heavily sanctioned and yet they speed-ran the left playbook to run their economy into the ground in record time. On the other hand, somehow sanctions didn't do much to damage Russian internal economy, as much as I wish they did - probably because even mafiosos and strongmen are not as dumb as leftists. OTOH^2 economically illiterate Erdogan was able to make lira crash without any sanctions. That was from just one stupid idea, whereas leftism is a whole stupid system.
Also, why should they need trade to provide basic services that most countries provide locally? Forget power, Cuba is/was one of the major, and most famous, tobacco producers. A middle-aged US man once told me he often goes on vacations to Cuba (flying thru Canada), because "girls there will sleep with you for a pack of American cigarettes". The regime is so incompetent they cannot even provide basic local goods that require ~no trade.