I was once looking into using nextcloud for an event. I might have had different requirements, though. But it does have something like Google Docs, it has forms you can send, it has a calendar. I don't think it has the ability to do email lists, though. But it does have a privacy-respecting video conferencing thing, which has almost all the features you'd expect. The thing it doesn't have is auto captioning. Or even a way for a stenographer to display manual captions.