I would like to know if I can have additional package installed to ploplinux.
nmap hwinfo dcfldd beep python3-pip sshpass pigz isc-dhcp-server
Yes, you can add more programs. There are various ways.
Either you compile the programs by yourself or you use the binaries from other distros.
You can add the binaries to the ploplinux/bin directory.
Or you can add the binaries when you extract for example the usr.sqfs (unsquashfs usr.sqfs), add the files (to squashfs-root/bin/) and compress the usr.sqfs (mksquashfs squashfs-root usr.sqfs)
Or you use the build tools for the Live Release.
nmap, python3-pip (pip3) and isc-dhcp-server is already part of Plop Linux.