Not a popular opinion, but I have a feeling that this is going to quickly go from your privacy is our responsibility to gatekeeping is virtuous, so we won’t let you do that.
1/ Interactive tutorials and quiz format like brilliant.org
2/ A Wikipedia like comprehensive wiki embeded with course website for all kinds of reference.
3/ An online community — could be a piazza/forum.
4/ A github like service integrated with course site specifically for that course where students can submit their projects and be evaluated by other forum members/mentors etc.
Isn’t the primary intent of having an offline place to cut off the distraction and to make it feel like a retreat? How can that be accomplished online?