Are you saying that this pleroma can run on a computer without Mastodon underneath it, at all ? As in, without a node.js , without any Ruby, and without any CWs ?
That sounds preposterous to me.
If it were true (and I doubt it), then companies would be selling networks without a Mastodon. This clearly is not happening, so there must be some error in your calculations. I hope you realise that Mastodon is more than just mastodon.social
? It's a whole system that runs the network from start to finish, and that is a very difficult thing to acheive. A lot of people don't realise this.
Gargron just spent $9 billion and many years to create 2.8, so it does not sound reasonable that some new alternative could just snap into existence overnight like that. It would take billions of dollars and a massive effort to achieve. Forkoff tried, and spent a huge amount of money developing but could never keep up with Mastodon. GNU Social tried to create their own system for years, but finally gave up recently and moved to Eunomia and Mastodon.
It's just not possible that a freeware like the Pleroma could be extended to the point where it runs the entire network from start to finish, without using some of the more critical parts of Mastodon. Not possible.
I think you need to re-examine your assumptions.