If your TV box is based on Android, there are good chances it will support Smart Launcher.
However, Android TV boxes are produced by many different manufacturers that usually run heavily customized versions of the Android OS. Sometimes these customizations result in the impossibility to set a third-party launcher as default or break some component required by Smart Launcher to work.
These kinds of issues are often not resolvable. Also, without the specific hardware is almost impossible for us to find and fix a specific issue. Because of these reasons, we currently do not provide technical support for Android TV boxes.