Well... why not both in one go?
sudo add-apt-repository ppa:kelebek333/nvidia-legacy
sudo apt update
sudo apt install linux-headers-5.4.0-81-generic linux-modules-5.4.0-81-generic linux-modules-extra-5.4.0-81-generic linux-image-5.4.0-81-generic nvidia-340
sudo echo "blacklist nouveau" >> /etc/modprobe.d/blacklist-nouveau.conf
sudo update-initramfs
sudo reboot
Once rebooted, test your graphics.
If no good, then reboot and Advanced Options for Zorin > select the 5.4 kernel and boot up - test graphics.