For clarification, on our end, we already restrict who can see the group, by using precisely the setting that Joshua mentioned. I don’t think we care about people seeing who is in the group (since we only show groups to members/admins). But it would be vastly helpful to be able to restrict who you can message based on group memberships, because we’ve had a number of messages sent to the wrong person.
Another thing that would help here is being able to have more than 6 people show up in the dropdown so that people can scroll down and find the correct user. Dunno if that’s closer on the roadmap.