Please follow the guide for feature suggestions and stick with 1 suggestion per thread. Otherwise users will have a hard time to actually vote for your thread (voting for all or nothing).
In your case, it appears almost all of those suggestions are already covered in existing threads. Please comment/vote in those threads in order to help us avoid distracting or cannibalizing votes. The exception seems to be describing a possible bug or issue in your setup for which logs might be helpful (online extras not playing).
There’s already existing suggestions discussing for Plex to support editions for tv-show libraries or different versions/releases of albums for music libraries (in addition to the existing feature for movies).
Local extras are a feature and they are working fine for editions. There’s an existing suggestion discussing for Plex to allow sharing of local extras across different editions of the same movie.
That sounds less like a suggestion but a bug report. It might be helpful to get logs from the player app where you experience this behavior for troubleshooting.
I’ve seen a few reports where users had issues playing the online extras due to certain restrictions in their home network.
Local extras are a feature, not only for movies (throwing in the support articles on how to add files as local extras for movies and tv-shows). Handling vor Other video type libraries is the same as for movies.
There are gaps when it comes to displaying local extras on all clients and for all tiers of tv shows (there’s a conclusive list which clients support displaying local extras for what tiers of a show in the support article linked above). There’s a feature suggestion discussing for Plex to support displaying all tiers of tv-shows on all apps (show, season and episode extras).
There’s an existing feature suggestion discussing for Plex to support .plexmatch files or adding Musicbrainz IDs to folders as matching hints for albums.
You should be able to set your library agent to Plex Personal Media to prevent your library from using any online metadata (or assets). If you’re using the Plex Music agent, setting your library to Prefer local metadata should already do that – at least for any file formats where Plex can read the embedded metadata (which should be the case for the common music formats).
For what library types are you missing this option?
As posted above… there’s a separate suggestion asking for an option to support different releases/versions of albums in music libraries. Beyond that, all library types should support different-quality versions of their items.
Edit: No tags needed to handle different-quality versions.
TheTVDb is not a master source of authority for TV series within Plex. That being said, Plex is sourcing metadata from different repositories – including TheTVDb. Though for most shows the role of “master source” appears to be TMDb.
There’s an existing suggestion for Plex to support crossover episodes across different shows (if that’s what you mean by cross-referencing).
