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.
I guess AirPlay is not possible due to Apple’s DRM.
not sure how relevant these may or may not be, but there are some client device implementations
EDIT: paste didnt work https://github.com/openairplay/open-airplay
The repository you linked has sadly not been updated in 9 years
while true, it would be more about the protocol and stuff.