If I upgrade to the 2021 4K apple tv, do I have to re-enter all my data
How to transfer data from 2017 Apple TV to 2021 Apple TV
How to transfer data from 2017 Apple TV to 2021 Apple TV
If you activate One Home Screen as iCloud feature, then your app details will be synced between all you Apple TVs.
Customize the Apple TV Home screen - Apple Support
↳ Keep apps and the Home screen up to date across multiple Apple TVs
If I upgrade to the 2021 4K apple tv, do I have to re-enter all my data