Sounds good. Maybe some sort of forum system, like https://github.com/hometown-fork/hometown (activitypub-based) or https://karrot.world or even an instance of lemmy ? Nextcloud is good as it has a lot of plugins for sharing photos and chatting etc. Video conferencing It would be worth looking at something like https://www.freedombox.org/ as it’s all self-contained, and might be easier to set up. at least as a proof of concept?

Yes. There are a few other chat clients that you can run relays for - Tox, SimpleX, Jabber/XMPP etc, which are worth investigating.