1.
Direct access to Plex / Kodi / Emby / Jellyfin / etc is not planned, and probably not feasible in the first place. That said one could use
Plain File Mode and then talk to Plex / Kodi / Emby / Jellyfin / etc via a
Custom Format Server. That would have to be a community project though.

That said, your use case is already thoroughly covered via
xattr metadata if you are using FileBot. You'll want to use
xattr metadata so that you can
instantly re-process previously processed files in the future regardless which media center software and version you happens to use at the time.

Organizing files with the
{plex.id} format as per
How do I organize files for Plex? is always a good idea because
xattr metadata do get lost easily because they're not typically visible to users.
2.
Smart Mode: Attributes primarily reads
xattr metadata but does resort to MP4 iTunes style atom tags if necessary and available.