No. The newest AppleTV 4K units are not 1440p, they are 4K, hence the name AppleTV 4K!
Get the newest and best which budget allows if you want to work in a Apple ecosystem. It will automatically detect the resolution of your TV and adjust the output resolution to work with your TV. So, if you only have a 1080p TV, then that is what it will work with. Just plug it in, and you are done.
Kodi is not supported directly in the app store on AppleTV or for Roku devices, it looks like it may be supported on Android TV devices. If your intention is to use Kodi, then I wouldn't buy an AppleTV. Of course, with the very limited app support of Kodi, I would just use Plex if I wanted things to be easy.
As mentioned above, AppleTV does not support APKs at all. Those files are for Android devices, which Apple most definitely is not.
Learn about .APK files and view a list of programs that open them.
fileinfo.com
Not sure what your goals are here, but if you want ease of use, then neither Kodi or APKs will be a part of that. It concerns me a fair bit that you are asking about Kodi and APKs, yet don't seem to understand that AppleTV isn't going to natively support them. So, what usage do you have for those add-on items? Why would you not use Plex if you want easy media file playback?
At the end of the day, Apple is as Apple does. If you buy into the Apple ecosystem, then it is all Apple all the time. If you don't, then it will definitely limit what you may expect to get. On the other hand, if it isn't supported by Roku, then it probably isn't software worth using, or requires a far more complex and knowledgeable end user.