@atomicpoet As I’m currently finding out, this is not trivial at all. The technical part is doable for a seasoned sysadmin but not for people unfamiliar with servers and software development. The real issue however is discoverability and resource consumption. My tiny instance was close to empty until I enabled relays, which then flooded the media cache with data at several GB/hour. CPU usage spiked to an average of 175% on a two-core VPS. Also, repeatedly, posts arrive with large-ish delays.
@hrbf There's another way to build federation without relays. But I can talk about that another day.