Apple TV 4K was introduced in 2017. However, some design features of this device was discovered only now. In particular, third-party developers found in the Apple TV hidden Lightning connector.
One of the first hidden connector found a jailbreak developer known under the alias @nitoTV. Later, the presence of Lightning in the Apple TV 4K was confirmed by other users.
The connector is located behind the Ethernet port and get access to it quite difficult. While it is unknown why Apple has equipped its TV console hidden Lightning connector. According to developer Steve Trouton Smith, it is used for debugging and testing the device.
The participants of the jailbreak community believe that there is a hidden connector that can help in hacking your Apple TV, or empower a jailbreak. However, while these are only hypotheses that still need to be checked.