I know you are just asking about Search. But I figured I would give the specifics in terms of input for clients including InputDirectoryObject() (since it can be used for search and other user input), SearchDirectoryObject(), and PrefsObject().
Plex Web recognizes InputDirectoryObject(). It will only accept the first InputDirectoryObject() on a directory level and if you want to allow user input for something other than search, they still have to enter that user input in the Search Dialog box at the top of that directory level screen. And Plex Web recognizes and includes universal search services in the overall Plex search.
The Roku now recognizes InputDirectoryObject() on both the Classic and Plex Pass version, so it won’t be long before it makes its way to and is approved by the Roku Store and is available to all users. The new Plex Pass version also recognizes SearchDirectoryObject() as an input option, but does not yet recognize universal search services or include them in the overall Plex search.
Support for the InputDirectoryObject()/Universal search services will eventually be added to all Plex player apps. It is just that right now there are a lot of Plex player apps that are either new or recently completely overhaluled (which makes them the same as a new app). So they are still in their infancy. That is why apps that have been around the longest have the most features. And Plex is first and foremost a local media media management program, so adding channel features are always going to have a lower priority than addressing issues with the media player or adding features for local media management.
And for PrefsObject(), it is recognized by PlexWeb and a few older clients. The trend seems to be toward choosing not to include Preference support in the new or recently redesigned Plex players apps and instead users will manage Preferences from the PlexWeb interface.
So just like all the other features of Channels, like adding or updating from the Channel Directory or deleting any channel, are now handled only by PlexWeb, since most people will set Preferences when they first install a channel and/or do not change often, Preferences for any channel can also be managed by users from the Plex Web interface.
