The porting guide requires img2simg and simg2img which are provided up to Ubuntu 22.04 and not later.
You can install these utilities using this snap:

sudo snap install android-platform-tools

sudo snap connect android-platform-tools:adb-support
sudo snap connect android-platform-tools:block-devices
sudo snap connect android-platform-tools:raw-usb
sudo snap connect android-platform-tools:removable-media
sudo snap connect android-platform-tools:network
sudo snap connect android-platform-tools:network-bind

sudo snap alias android-platform-tools.img2simg img2simg
sudo snap alias android-platform-tools.simg2img simg2img