Browsing a media browser on HA to start media on a Chromecast is possible.
But starting a specific show with an action call seems impossible.
It should be as easy as with plex, knowing that Jellyfin is FOSS compared to Plex.
This would allow many plex users to jump board from a paying solution; to an open sourced one!
entity_id: media_player.google_speaker
media_content_type: music
media_content_id: 'plex://{ "library_name": "Music", "artist_name": "Adele", "album_name": "25", "track_name": "Hello" }'
entity_id: media_player.google_speaker
media_content_type: music
media_content_id: 'jellyfin://{ "library_name": "Music", "artist_name": "Adele", "album_name": "25", "track_name": "Hello" }'