Raspberry pi only allocate 9GB to /dev/root where more to other partitions

Assuming your SD card is >9GB, you will have to resize the root partition to take up the remaining space on the card.

You would usually do this with the raspi-config utility however if that is not available you could try gparted instead.

Check this gist for instructions on how to instlal raspi-config on Kali Linux:

apt-get update
apt install lua5.1 alsa-utils psmisc && apt --fix-broken install

wget http://archive.raspberrypi.org/debian/pool/main/r/rpi-update/rpi-update_20200409_all.deb
wget http://archive.raspberrypi.org/debian/pool/main/r/raspi-config/raspi-config_20201108_all.deb
dpkg -i rpi-update_20200409_all.deb raspi-config_20201108_all.deb