I would be happy if Nextcloud Photos would eventually offer a complete replacement for Google Photos 
And I think more can and should not be expected in this direction imho.
Apart from that, Jellyfin and Nextcloud cover completely different usecases and partly have completely different requirements for the components involved. And personally I don’t need to have my movie collection in the same place as my documents and photos. I honestly prefer Nextcloud to focus on improving allready implemented features like “Fotos” (which of course could make use of some kind of transcoding too) instead of adding new functionality for which there are already specialized products that do their specific job better anyway.