Hello! We don’t currently have plans to enable video screenshots for Apple TV 4k (1st Gen) or Apple TV 4th Gen (and for anyone who is confused by the naming, Apple TV 4th Gen is one version older than the Apple TV 4k 1st Gen). We did quite a bit of testing on these devices and found that the capabilities of that hardware couldn’t perform to an acceptable degree.
This feature is available for Apple TV 4k (2nd Gen) and Apple TV 4k (3rd Gen, which is the latest model), so if you do decide to upgrade your device in the future, it will work on those.