This is just an ultra quick outline of what self-hosting Roomy looks like.
We aren't quite ready to have people self-host the whole thing yet, but we are very setup for it and that will be available once we can get the app more stable.
Self-hosting any of these components will not isolate you from the rest of the network. Any Roomy space can be joined from any Roomy app regardless of which components might be self-hosted, even if different components are self-hosted by different people / organizations.
You can choose to self-host each of the different Roomy components with or without the others in any combination.
If you just want to customize the frontend or host it under your own domain, you can just host the frontend.
If you want to allow users to register for chat without having another ATProto account, then you can host the PDS.
If you want to have self-sovereign control over your community's chat messages, you can self host the Leaf server.
The Frontend
The app, hosted at roomy.space can be self-hosted if you want to customize it. Another reason you might self-host it is if you just want to have people be able to chat in an app on your domain, like chat.example.com.
In that case you could adjust the UI to only show your chat space when people use that domain.
They'll be able to login with any ATProto account and chat in your space on your domain, and if they later go and log into roomy.space, then they'll see your spaces in their list of joined spaces.
They can choose to participate with your community from the main roomy.space app at that point, or any other Roomy client.
If you wanted, your community could say, "Join our in Roomy" with a link to the roomy.space app, "Or our chat here", with a link to chat.example.com.
If you want people to be able to register for chat.example.com without having another ATProto account, then you'll also have to host a PDS.
The ATProto PDS
The ATProto PDS is used primary for authentication in Roomy. A minimal amount of public data is stored on the PDS, and eventually it may store optional archives of your Roomy data.
For now, but most-likely not in the future, the PDS is also used for hosting all uploads, like when you share images.
Note that while we are currently using the reference PDS implementation by Bluesky for Roomy's own hosted PDS, you could use any of a number of community-developed PDS implementations.
The main reason to host a PDS is if you want to allow people to be able to register a Roomy account without redirecting them to another site like Bluesky.
The Leaf Server
The Leaf server is where the chat messages and almost all of the other Roomy data is stored. It's Roomy's customizable, realtime stream engine.
Self-hosting the Leaf server ensures that you have complete control over your community's data.
Each different Roomy space could be hosted on a different Leaf server, and everybody can still use their same account and app to join them.
( Future ) Web Engine
In the future there will be a service that can render your Roomy space as webpages which can be important for search-engine-optimization.
We have some plans for this, but there is still a lot to work out on exactly how that will be done.