i just want to add, that you can theoretically run a relay on your own device, if you have a VPS with wireguard and a reverse proxy, and a firewall filter that only permits you to access it from your wireguard connected devices

but this is at best a way to have your own personal cache of your notes, it doesn't make it very easy to have other users on it as well, for that you need some kind of tool that scrapes other relays to push them to your relay