is a powerful OS image flasher built with web technologies to ensure flashing an SDCard or USB drive is a pleasant and safe experience. github 
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It protects you from accidentally writing to your hard-drives, ensures every byte of data was written correctly, and much more. It can also directly flash Raspberry Pi devices that support USB device boot mode page .
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USB Host Boot Mode page
Raspberry Pi 4 USB Boot Config Guide for SSD / Flash Drives page
Booting FreedomBox from USB or using USB stick as root filesystem page
> The UEFI firmware is installed on an SD card and the root filesystem on a USB drive.