preston the usb stick found by ImageWriter
KaOS does not have ImageWriter, the app is Isowriter
, the former is an application from OpenSuse.
You did not mention before whether you are looking for a Linux or Windows solution, if for Windows and Imagewriter doesn't work, you can use Rufus (not tested enough to add to the KaOS docs as fully supported), if you use the dd option in Rufus settings, do not use the default, that will fail on install.