Sharing guide
Family sees Jellyfin. Your friend sees Seerr. You see everything.
You'll need
Already have your apps on Seawise.io? This takes a couple of minutes. If not, set that up first.
In seawise.io, go to Portals and click New Portal. Tick the apps this group should open, and leave everything else off.
Open the portal's sharing settings and add each person's email. Only those people can get in.
Remove an email any time and that person loses access within 30 seconds.
Copy the portal link and send it however you like. They sign in with the email you added, using Google, GitHub or an email link, and see only the apps on this portal. Nothing to install.
They're on another portal that includes it. A person can open every app on every portal they're added to, so check each portal's people list.
Make a small portal with the extra app and add just them. They'll see both portals.