@hybotics There is the Counter.social example as a different way. It started as a Federarted Mastodon Instance but became a more isolated aspect when, for “security” reasons Federation was turned off. Also, the founder of Mastodon isn’t so keen on that non-Federated part, but it’s an option.
You would certainly be able to set up an instance then isolate it from outside by shutting down Federation. It will work with existing & new Mastodon app, too.
// @matigo