kambian is the name that has been given to this new distribution project based on Kali Linux and Armbian. That is, on the one hand it unites the good of a distro designed to perform security audits, ethical hacking, or pentesting. A well-known project founded and maintained by Offensive Security Ltd. And on the other hand it uses that other operating system project specially designed for ARM development boards. In other words, Karmbian is a Kali Linux build using Armbian Tool Chain and BSP (Broad Support Package).
Ultimately, the result is Karmbian, a pentesting distro that can work about ARM devices. For example, you could install it on your SBC Raspberry Pi, or on the ROCK64, Ordoid N2, on laptops like the PineBook Pro, and a long etc. Although it is true that if you wanted to use Kali Linux on ARM chips it was already possible due to the images that exist in the Offensive Security official website.
However, it never hurts know alternatives and more similar projects like kambian. In addition, you should know that Karmbian has support for the Raspberry Pi 4 board, and all those supported by Armbian, as well as being optimized for Rockchip RK3399 chips.
Karmbian has a number of available images for your download for free from their site on GitHub in its Karmbian 2020.08 version (current at the time of writing this article). Although at the moment there are only a few officially supported ARM devices, their developers promise to gradually add more.