They have hundreds of servers running today by volunteers, there is little cost of entry since even cellphones can be used as servers (nodes) to keep you private notes or keep the notes from people you follow.
There is now a file sharing service called "Blossom" which is decentralized in the same simple manner. I don't think I've seen there a way to specify custom domains, people can only use the public key for the moment to host simple web pages without a server behind.
Many of the topics in your page are matching with has been implemented there, it might be a good match for you to improve it further.