With the launch of the Apple TV 4 Jailbreak tool, here is a guide to jailbreaking please note NitoTV has not yet been updated.
1) Download Cydia Impactor for Mac, Linux, or Windows to your computer.
2) Download the liberTV app.
3) Connect your Apple TV 4 to your computer via USB-C and launch the Cydia Impactor app.
4) Make sure that Impactor is showing your Apple TV as connected in its interface, and then drag the liberTV.ipa file onto the Impactor window.
5) Hit Start and Impactor will prompt you for your Apple ID and password. Enter them. If you have two-step verification turned on for your Apple ID account, you cannot enter your normal password. Instead, log into the Apple ID page, and request an app-specrfic password. Enter that into Impactor the password field.
6) Impactor will now push the jailbreak app to your Apple TV 4. Once it’s complete, disconnect the Apple TV from your computer and connect it to your TV via HDMI. The liberTV app should now be visible on your tvOS home screen, launch it
7) On the following page, select the options you want to use to jailbreak your Apple TV. It’s recommend selecting all of them for the full experience.
8) Hit the Do it! button at the bottom of the screen and wait. The app will try to jailbreak the device.
9) Here the process will either fail and reboot, or report the device successfully jailbroken. If it fails, simply launch the app again and retry; Its normal for the app to fail some percentage of attempts.
10) Once the app reports that the device is jailbroken, you are done! You can now SSH into your device with Dropbear, sideload apps.