Those function could be easily used by themes or plugins willing to integrate WP/LR Sync.

global $wplr;

Get information related to collection:
get_collection( $id )

Get tags/keywords related to a media entry:
get_tags_from_media( $mediaId )

Get media entries related to a tag/keyword:
get_media_from_tag( $id )

Get media entries related to a collection:
get_media_from_collection( $id )

Get enhanced media entries related to a collection (all the data should be enough for a theme):
get_gallery( $id )

Get collections related to a media entry:
get_collections_from_media( $mediaId )

Get collections in a folder:
get_collections_from_folder( $folderId )

Get the hierarchy of folders:
get_hierarchy()

Get the hierarchy of tags/keywords:
get_keywords_hierarchy()