One thing is prioritizing security. There's a number of known flaws, of varying severity, which is why most people would recommend not exposing Jellyfin to the Internet.

Perhaps they could set up a second project, a Jellyfin meta-library, whose whole goal is to be exposed to the Internet. You stand that up, give it access to other Jellyfin servers, and it handles the work similar to STUN of connecting you to media on those servers. This would make it so people could share easier.