The developer working on integrating network display functionality into GNOME Shell shared short video clip to the GNOME sub-reddit […] the feature adds a “screencast” button to the row of actions in the Quick Settings menu. Clicking this opens a modal picker where the user can select any Miracast or Chromecast compatible displays on the network.
It seems to support Chromecast though
Isn’t chromecast based on Miracast?
It’s certainly not based on Miracast. Chromecast is built around applications running on the Chromecast itself while Miracast is merely a combination of WiFi Direct and a video stream.
Google does offer SDKs for Chromecast for a wide range of devices. You can program the thing to play a video through Javascript, so it’s probably not very difficult to add Chromecast support once you’ve got the video stream stable and running.