Not available yet

No public Nulx ISO exists today, so there is nothing official to write to USB media.

Future checklist

Download the ISO from https://nulxlinux.com/download.
Verify its published SHA-256 and signature.
Positively identify the removable device.
Use a reputable image-writing utility appropriate for your operating system.
Reboot and select the USB device in firmware boot settings.

Writing an image destroys the existing contents of the selected device. The final guide will include tested tools and screenshots after the Beta artifact passes USB boot validation.