In fact from the little responses I got asking the responsible people at Process One it sounds a bit like they only plan to make it work for out-going federation, meaning you can participate in rooms and contact people on Matrix, but not the reverse. This is likely to fake the DAG and thus not have to run a full Matrix homeserver like federation, but that is only my rather unqualified idea. (However this is corroborated by the Element CEO recently musing on HN about a kind of two class federation where not all participating servers run the full stack).

Anyways, right now it really only does outgoing 1:1 chats and I haven’t seen much active development on it either.