Communists that focus on voting are delusional (in my opinion) but like all reformists they view the existing government as the mechanism to make widespread change.
The only state in my country that has a communist party in power has been consistently leading national rankings in education and health, so I guess they’re doing something right.
It really depends on who your friend is, and who they are trying to defenf against.
If the US ( or Russian / Chinese) government really wants to access an internet-connected device, they can do it; what app you are using doesn’t even matter. For example, most people use the default Google keyboard, which could be compromised.
If the concern is about local goons / employers / coworkers, then both Telegram and Signal are more than enough to stop them prying.
As for whether to use Signal or Telegram, Signal has end to end encryption enabled by default, while in Telegram you have to switch it on for each chat. On the other hand, Telegram has the best UI among messaging apps hands down.
Just saw this on the news community. The linked article goes into some detail. I don’t know if these policies will achieve ‘full communism’ (or even if that would be a good thing), but education and health are good things for governments to focus on whichever way you look at it.