I've found the cmdpad pkg in the openwrt packages github repo, but for some reason that pkg is absent in:
http://downloads.openwrt.org/releases/18.06.1/packages/mipsel_mips32/packages/
therefore
# opkg update
...
# opkg install cmdpad
Unknown package 'cmdpad'.
Collected errors:
* opkg_install_cmd: Cannot install package cmdpad.
Why hasn't it been included in the openwrt_packages feed?