Dedicated tourism enclaves
The developed cays function as dedicated, state-managed tourism enclaves. Access is often controlled by causeways and checkpoints, and the land and infrastructure are closely tied to the state and to tourism ventures. This is about as far from a private residential market as a Cuban location can be.
Because the cays are organised around resort tourism rather than resident communities, the domestic home-sale market that Decreto-Ley 288 of 2011 created for Cuban citizens and residents has little practical presence there. There is no ordinary stock of privately owned condos being traded on the cays, because these are not places where a settled population buys and sells family homes in the first place.
Foreign capital means approved projects
Where foreign money is involved with the cays, it is through Ley 118 of 2014 and state-approved tourism projects and joint ventures, not private condo ownership. Hotels and resort facilities are developed institutionally. An individual foreigner does not acquire a personal beach apartment on a cay as a side effect of that investment activity.
So the practical answer for a private buyer is essentially no: the cays offer scenery and holidays, not personal title to a seaside home. If a pitch presents a cay 'development' as though it were a simple personal purchase, that framing collapses the very distinction, between approved project investment and private ownership, that Cuban law keeps firmly separate.
What the cays are actually for
It helps to see the cays for what they are: managed holiday environments. The realistic way to enjoy them is to visit and stay in lawful accommodation. If your goal is a long-term base near the sea in Cuba, the mainland beach towns, combined with lawful renting or a genuine residency route, are far more grounded than any notion of owning on a cay.
Thinking of the cays as a place to holiday rather than to hold title keeps your expectations aligned with reality. It also keeps you well away from the informal arrangements that tend to circle the most glamorous and least attainable Cuban beach locations.