https://reactos.org/download/, https://reactos.org/wiki/LiveUSB.
(Off-topic: https://reactos.org/wiki/A_Layman%27s_Guide_-_Installing_from_a_USB_memory_stick). https://reactos.org/wiki/Installing_ReactOS.
sudo dd if=ReactOS.iso of=/dev/sda bs=4M oflag=direct status=progress #https://dragonserw.ru/wiki:reactos