There are however little more than tech demos for it. There's still a significant body of unresolved questions. Theres very limited amount of effort going in. But there are some very nice libraries too, such as https://github.com/youtube/openscreen-rs .
Not an answer for most people for today, but if folks are feeling agentic, this is where I would burn my tokens. Your timing is actually quite incredible; I picked up my project again & have been burning the last tokens of my weekly quota on open screen protocol today!
(Don't get me started on what a frelling turd show MatterCast is. Last I checked it was for native apps, and had no means to distribute or find programs, only could work with apps already on the castee. Miserable evil capture-computing shizzle, with zero aspirations to ever allow the just works interoperability that made Cast so amazing. Truly captured device ecosystem, of Official Partners anti-consumer villainy. Vomitously disgusting, makes me feel much worse about Matter in general seeing how wretched that looks.)
Generally I recommend -- like with Chromecast -- using your phone to launch and control apps, using your phone as the locus of control. Maybe having a gyro mouse or Bluetooth keyboard connected to your pi... but the originally Chromecast was input less, was a networked output. To cast a thing was just to tell the display or speaker: go to this URL. And then to have some communication channel open from your phone or casting computer to the display or speaker. Any web page can use Presentation API to start a cast, to extend itself to another device. It's amazing. https://developer.mozilla.org/en-US/docs/Web/API/Presentatio...
Under that model, there is no remote. The phone is the remote.
To run a regular TV is harder. Yeah I don't recommend trying to host a whole media system. You can run jellyfin on many TVs or maybe plex. Some rare brave souls go and build their own castles in the sky. Personally I feel strongly though that people clutching at remotes & making the tv itself the locus control are doing it wrong and that the cast model is fundamentally much better, and that the tv itself ought be a blank slate. https://arstechnica.com/gadgets/2024/07/broken-linux-laptop-...