Functionally, the Apple TV 4 works just like the 4K. Older generations beyond that, are showing their age and I find that the 3rd generation is laggy and the 2nd generation is crashy. The 4K no longer has a USB port, so for app development, you’d best get used to remote debugging.
https://www.amazon.com/Apple-TV-64GB-Latest-Model/dp/B075NHCSS4

