Help & troubleshooting for channels on your Roku device, including adding/removing channels, logging in to, authenticating, or activating a channel, channel-specific playback issues, assistance contacting channel publishers to report issues, and adjusting channel-specific settings.
Just try it and find out. Roku devices don't need to be connected to a TV with cable for Roku channels to work. They're completely independent of each other. You may need a cable subscription to authenticate certain Roku channels, but that has nothing to do with having to have a cable box connected to the same TV as a Roku.