The US government just allowed an Icelandic airline to offer flights between the US and Cuba. But buying tickets come with restrictions.

There is now a way for North Americans to go to Cuba.
The home country of the airline is Iceland. The flag carrier from the Land of Fire and Ice will take passengers between Cuba and both Florida and Texas.
The US Department of Transportation gave the go-ahead for 170 charter flights between Havana, Cuba and the US cities of Miami, Orlando, and Houston.

The average American won't be able to buy a ticket on one of the flights as the US government limits what types of travel to Cuba is permitted by US citizens, according to the Department of the Treasury's Office of Foreign Assets Control.

American citizens are not allowed to travel for tourism purposes.

A family is visiting.
The official business of the US government and foreign governments.
Journalistic activity.
Research is professional.
Education activities.
There are religious activities.
Athletic teams or athletes compete in athletic contests.
There is support for the Cuban people.
Humanitarian projects.
Private foundations, research or educational institutions have activities.
Information or information materials can be exported or imported.
Certain authorized export transactions.

US airlines don't likeIcelandair.

The DOT's public charter system allows for 3,600 annual flights to operate from the US to Cuba. The request to fly between two countries that aren't its homeland was objected to by US airlines.
Swift Air, World Atlantic Airlines, and Global Crossing Airlines are three US airlines that primarily offer charter services using passenger airliners.
Mark Schneider, an attorney for Global Crossing Airlines, wrote to the DOT that the primary reason for requesting approval for 170 additional flights was to impose an economic hardship on the current US air carriers. In response to Global Crossing and Swift Air, Icelandair claimed that it isn't taking slots away from any carriers and that its charter partner had already ruled out other US carriers.

Jonathan Fuchs, the general counsel for the Americas, wrote a letter to the DOT, saying that he didn't understand how it was taking market share to the detriment of US based carriers.

The baggage holds of the Boeing 757 aircraft is where the advantage is over US carriers. 54 bags had to be left behind because of space constraints on the first flight from Florida to Havana.

Smaller aircraft such as the Boeing and A320 families wouldn't be able to carry the same amount of baggage. The flights were authorized by the DOT despite the fact that there were still more slots available for US airlines.
Airlines have been adapting to the new reality of air travel during the COVID-19 Pandemic, and Icelandair has scaled back its trans-Atlantic flights due to travel restrictions and fluctuations in demand. Even if the flights don't touch Iceland, the new route will give the airline an additional revenue stream.
Between February 1 and May 31 there will be 170 flights.