Plex for Android TV and Android boxes depends on a Plex Server to organize and play movies, TV series, etc. Some people may not have a computer to install the Plex server and end up choosing another app like Mizuu.
I would suggest that Plex for Android / Android TV has the feature to play and organize all my media on an external storage by USB or LAN without a server and only for Plex Pass users.
Optionally we could choose another app to play the selected media.
Thanks and sorry my bad english.
Marcelo Gomes