None of your arguments are really an answer to anything.
Every app, telegram, simplex, ICQ are single points of failure - by design - whereas services like xmpp/jabber or even the self hosted variants of signal, simplex or matrix don’t have these problems. But they don’t do that. At least nothing that I heard of.
I think the reality is much more that most of the Nazis are inherently not constructive. They don’t create anything, they have no real vision, just hate for whatever group they think is worst right now.
They are literal leeches, they take over what they can get. Telegram, Twitter, now SimpleX. Volk ohne Messenger, if you want. There is exactly one platform that was created by them, truth social, and that’s a grift by Trump and his team, not something growing from within the community.
None. There is no model that can output anything even remotely usable on that tiny amount of RAM and certainly not using the few CPU cycles your vps has to offer.