I think you may be conflating the terms "roku channel" and "Roku TV" A "Roku TV" is essentially a TV with a roku built-in, so you get the over the air live TV stuff and the streaming all in one device. With a streaming stick, the live TV is usually handled with the TV that you connected the stick to. ie: you use your TV remote to select the antenna input.
Of course, there are various streaming apps that show some of the same content that you might see on live/OTA TV as well. One of these apps is called the Roku Channel.