You would just need to create for example .xml file with proper rss tags etc, put that on a web server accessible by the players and have the ticker widget pointed to it.
It could be even in the CMS /web/userscripts folder (if you’re on 1.8 series) - for example Can you load PHP files from media library
but in your case that would be .xml file and the path to it would be in ticker widget.
An example of a feed - https://ceu.xibo.cloud/mediarss/feed.xml
If you will not have images there, then you could just have title and description tags