While waiting for feedback on privacy related stuff, I almost finished basic group support. That means you can soon create groups, join them (or request joining them in case of closed groups), and viewing their details. Invitation is not possible yet (which is especially relevant to secret groups), but will do that tomorrow.
Here is the very basic outline on groups. I will extend this documentation soon(ish).
This instance is dedicated to the members of the Polonkai family. If your surname is Polonkai, you are more than welcome here.