Apple TV is a streaming box. It would most certainly plug into your Samsung TV and work fine. You might be thinking about the Apple TV app that runs on some smart TV platforms. This is just Apple's app. This doesn't allow third party apps that run on the Apple TV hardware, to run on your TV. So if you wanted to move to the Apple TV device, you would be able to.
Also, consider the fact that when you're using Channels for your TV watching and recording, app support like YouTube on your platform doesn't matter. In fact, your provider doesn't matter either. Your provider only becomes a means to get access to the TV streams. You could change your provider to anything you want to get the channels you want.