Great blog post, but unfortunately from my experience with my kinda tech-friendly family, i can tell you that not exposing service publicly is an absolute UX killer.
Nobody uses the local nextcloud because they just don't think they can rely on it, it doesn't always work from their perspective, and is too finicky to use, because it needs an external app (Tailscale).
This can be only fixed when the app itself can trigger a vpn connection, and I don't think this is going to happen any time soon.