Channels DVR on Emby/Plex

Is there an add-on or way to get channels on either of theses?

No. Channels is its own independent standalone app and sever software.
Emby and Plex and Kodi, are competitor products/services.
They have their own Live TV and DVR and home media server features and implementation.

It is like asking if you can get TiVo to work on a Xfinity CableBox....2 completely separate competitor products.

You can point Plex/Emby at your Recordings folder and access them that way.