Setting up remote access for Jellyfin felt pretty trivial for me like 2 years ago when switching away from Plex. No hiccups that I can recall whatsoever. Except for maybe the nginx reverse proxy configuration, but the documentation made it decently straightforward, but that step isn't strictly necessary to get remote access working; that was just something I wanted for my particular setup.

And I wouldn't call the Jellyfin UI janky at all. I use it every day and can't think of any common issues I encounter when using it. There surely are quirks with some features, but I find them few and far between. I recall Plex having its own UI quirks back when I used it.