A:Answer Peacock is included on the list on supported cast-enabled app. However, both TUDB and beIN is not included on the list of supported cast-enabled apps. But, if you have an Android device, you can mirror your phone screen to the Chromecast to watch content.
You may check the following support article for more information:
Cast your Android screen: https://support.google.com/chromecast/answer/6059461
Keep in mind that while Chromecast doesn't require any subscription to use, you will need to subscribe to the services of some partnering apps such as YouTube TV, Netflix, Hulu, HBO Max, Brit Box, Prime Video, and many more to stream movies and other video contents. List of cast-enabled apps: https://store.google.com/us/product/gtv_apps_and_partners