Is it possible to develop a custom Backdrop App for Google Chromecast instead of using Google's Backdrop feature? It doesn't support some features and I have some ideas, so want to see if that is possible. Documentation didn't provide me that information. Thanks.
No, that area is not open to developers to change; users can decide on the source of content there (images from various sources, news, etc) but beyond that, there is no access to backdrop for developers.