With the enshittification of streaming platforms, a Kodi or Jellyfin server would be a great starting point. In my case, I have both, and the Kodi machine gets the files from the Jellyfin machine through NFS.
Or Home Assistant to help keep IOT devices that tend to be more IoS. Or a Nextcloud server to try to degoogle at least a little bit.
Maybe a personal Friendica instance for your LAN so your family can get their Facebook addiction without giving their data to Meta?
“Technically correct” is the best form of correct. Though having tried setting up Wireguard in the past, having a dead-simple solution like Tailscale might be worth trying it out, especially with the 100 device free tier