It supports built-in snapshots, allowing you to save the state of your Windows 10 ARM environment and roll back if an update or app installation fails.
Unlike "raw" images, a QCOW2 file only takes up space on your physical drive for the data actually written inside the VM.
Tools like raspiduino/waq provide scripts to automate the download and configuration of Windows 10 for ARM on QEMU. 2. Create Your Own Image (Recommended)