Can you add a google photos type app? Maybe Piwigo (it has a good mobile app) or OwnPhotos (it has face/object recognition). Lychee doesn't have a mobile app or face/object recognition.
Can you add some communication apps like Matrix Synapse or Ejabberd? Mattermost is walled off from the outside world.
Can you add some social apps like Pleroma or Mastodon?
Otherwise, Matrix+Riot is being worked on already. Mastodon is similarly mostly done https://forum.cloudron.io/topic/1136/mastodon-microblogging
Our latest addition is now OnlyOffice, currently in testing mode.