The code to make bots are on GitHub and people also sell bot scripts you can buy to run on your own server or a third party server so as long as you can create an account and sign the keys over to a bot/script it can do whatever you program it to do
Well not really as a “social media” your goal is to reach as many people through as many channels as possible so you need to use public infrastructure to do that
You can have closed networks like sphinx or Zion which are self hosted so you host your own data but these options won’t be popular with the normies not that it’s a bad thing it provides a barrier to keep a lot of nonsense out and only speak with commuted real users quality over quantity
I just see the ecosystem as a way to reach people who are half way in and hopefully I can get them to rethink their biases and reevaluate the marketing talk and consider real sovereignty and privacy tools