"Apple shall make available the possibility for a third-party connected physical device to become an AirPlay receiver, i.e., allowing the iOS device to cast content to a receiving third-party connected physical device, to all interested third parties independently of the product category, for video, audio, and screen mirroring”
Re AirPlay and Chromecast et al
"Centralised availability: Apple shall allow third-party casting providers to centrally provide their casting solution on iOS, e.g., through an extension, such that end users who install the casting solution can access the third-party casting provider in any third-party app that uses standard media playback APIs without the need for the third-party app developer to integrate an SDK in their applications.”