I think there's an issue in your thinking: you're only approaching this situation in terms of technology. This is in fact the reason why the "solution" in western countries is open source and decentralization: we think it's a technology problem, so the solution is technology. But, like most things, it is inherently a social problem.

Cuba has been under embargo for decades now, and its internet has been heavily censored since; they haven't known how ingrained FAANG are, how ubiquitous Android and iOS and twitter and all those things are. For us, Mastodon is an alternative to Twitter; if there never was an ubiquitous Twitter to begin with, would we have created a heavily asymmetric client-server architecture ?

Sneakernet is the digital continuation of gathering with people and exchanging. Cuba already had an intranet between interconnected homes. The social shape always defines the communications shape, so the reason a sneakernet works there is not enough to say that a sneakernet would work here.