The official doc seems too complicated OpenWrt on VirtualBox HowTo
- Download and install VirtualBox. On Windows add to PATH envs
C:\Program Files\Oracle\VirtualBox
- Get an OpenWrt image
openwrt-x86-64-combined-ext4.img.gz
from targets/x86/64/ folder. Direct snapshot download - Uncompress the image:
gunzip openwrt.img.gz
- Convert it to native VirtualBox format:
VBoxManage convertfromraw --format VDI openwrt.img openwrt.vdi