If you’re up for using Jellyfin and have satellite devices, you can check out something I’m working on to achieve this: github.com/MattMckenzy/Homehook
The main branch was compatible with chromecast devices, but I’ve stopped maintaining it in favor of the v2 branch, where HomeHook communicates directly with satellite devices through HomeCast.
Let me know if you have any questions about it, always glad to help!