Hardware requirements?
KDE is a modern Desktop Environment which can make use of most of any graphics or sound card capabilities. This does not mean KDE can’t be made to run on very low-end hardware, but in general there are better options available for such systems (OpenBox for example).
The very minimal needed for hard-drive space is 8 Gb, but 25 Gb is recommended as minimal. KaOS will install with 1 Gb of RAM available, though a much better experience will start with 2 Gb of RAM. Since only x86_64 packages are available, a 64 bit capable cpu is needed.
As with any rolling distribution, updates are frequent and can be large, so a reasonable fast internet connection (dial-up will become very cumbersome) and available monthly data of over 2 Gb are recommended.