I don't know what you mean by saying Mutual Aid networks "already implement what I'm talking about." Are you saying Mutual Aid networks are spreading theory? Just want clarification here, charity is a good thing but that's not what we were discussing to my knowledge.
As for the individualism and isolationism, that's due to the class characteristics of the US Empire. As it depends on Imperialism, and has a large population of petite bourgeoisie and labor aristocracy, it is much harder to get genuinely leftist ideas to penetrate. The solution, however, isn't to contribute to that by obscuring your intentions. A right winger suddenly thinking universal healthcare is a good idea won't change the fundamental systems at play.
As for Cuban immigrants, it has been a long time since it became Socialist, and the Land Reform Act enacted. The descendents of these Cuban Exiles largely side with their parents, who tended to be against the Socialist revolution, as they were among the ones who lost out. Other exiles leaving due to the conditions imposed on Cuba by the US Empire's brutal trade embargo aren't likely to be convinced either.
You have to meet people where they are at without obscuring, otherwise you allow them to control the narrative.