So we set this forum in place.
It is a place for users and contributors to communicate in a more accessible and less constrained way than GitHub.
It might be a good idea to have a (easy-to-join and accessible to non-techies) instant messaging channel at some point, so it can used to answer quickly to simple support requests, be used for meetings and generally discuss about the project in a less formal way.
Also, I’d like to have a blog so we can publish the announcement and updates about the project (what we do, why and let users know about ongoing decisions). Plume might be a good candidate since it is using ActivityPub.