So even something as basic as opening a bank account in such circumstances isn't possible, as no bank will cut themselves off from the entire worldwide banking system just to provide you an account.
[1] https://www.miamiherald.com/news/nation-world/world/americas...
Cuba is poor because Cuba is Communist. They can trade with everyone except the United States, if they had anything to trade with.
The US sanctions do serve as a wonderful excuse for the Cuban government to blame the poverty they inflict upon their own citizens on the United States. Plenty of gullible people outside the country fall for it as well.
The statue gives EU companies the ability to recover damages caused by the Helms-Burton Act. They even threatened to counter-sanction US companies making Title III complaints.
The result of multiple countries passing similar blocking statues was that the Helms-Burton Act had been suspended by every President from 1996 until 2019 when Trump decided to reactivate it.
According to an EU report on the statue, there have been threats of US legal action, but no mention of any EU company has actually been sanctioned.