Kali Linux is now compatible with the Raspberry Pi 4. Currently, the distro is only available as a 32-bit OS, but Offensive Security is planning on releasing a 64-bit version soon. In the meantime, security aficionados who have a spare Raspberry Pi 4 lying around can head over to the Kali Linux site and download the distro image.
https://www.notebookcheck.net/Kali-Linux-now-available-for-Raspberry-Pi-4.427225.0.html