Sometimes it's nice for testing purpose to have the OpenWRT userland available locally. Since there is an x86 build available one can just run it within qemu.

gunzip openwrt-21.02.1-x86-64-generic-squashfs-combined.img.gz
qemu-img convert -f raw -O qcow2 openwrt-21.02.1-x86-64-generic-squashfs-combined.img openwrt-21.02.1.qcow2
qemu-img resize openwrt-21.02.1.qcow2 200M
qemu-system-x86_64 -M q35 \
  -drive file=openwrt-21.02.1.qcow2,id=d0,if=none,bus=0,unit=0 \
  -device ide-hd,drive=d0,bus=ide.0 -nic user,hostfwd=tcp::5556-:22
# you've to change the network configuration to retrieve an IP via
# dhcp for the lan bridge br-lan
vi /etc/config/network
  - change option proto 'static' to 'dhcp'
  - remove IP address and netmask setting
/etc/init.d/network restart
# now you should've an ip out of
ssh root@localhost -p 5556
# remember ICMP does not work but otherwise you should have
# IP networking available
opkg update
opkg install curl