@nicolasmaia @loweel Here you go: https://social.umeahackerspace.se/local/ostatus.pdf
The relevant RFCs (or other specification) which are referenced are pretty easy to find (Atom syndication format, various extension to Atom, # Pubsubhubbub, Salmon, FOAF).
What's not mentioned in that document is the designation of WebFinger as RFC7033.

It would be greatly appreciated if you could put up some barebone structure which I could just fill in as I have time (and anyone else who knows the !ostatus suite), since it currently feels like too big a step to do everything myself from scratch. Please help make it easier for new developers, just like you yourself want it.