I'm not sure how they could have assisted with anything, they basically have no medical supplies[1][2][3][4]. And before you bring it up, no medical supplies aren't covered by the embargo, they get a special exemption since the 90s.
There's a US law that says any ship that docks with Cuba can't dock with the US. Considering that modern shipping relies on big ships making many port calls, this law restricts Cuba's access to stuff like medical supplies.
There was a time where supplies was the issue, and I doubt Cuba could help there. But there was also a time when medical labor was the issue, and Cuban doctors could have helped with that.
Probably not. They definitely wouldn’t have had training with modern medical equipment, which isn’t available in Cuba. Also we take a dim view here on slave labor which is the most accurate way to describe the Cuban medical mission.