This was linked to today on HackerNews: https://ntfy.sh
Since this is open-source and HTTP based, it sounds like a perfect companion to TT-RSS. I imagine that it could be easily bundled in the docker image, and allow to get easily notified when new posts arrive, using the most basic HTTP pub/sub implementation that most modern browsers implement already, thus lifting the requirement for any additional plugins (Pushover/Pushbullet, etc.)