KUAL

KUAL is marked as part of the installation process on Kindle Mod Wiki. Follow their guide:

The installation of Update_KUALBooklet_hotfix_*_install.bin may fail if there is not enough free space on your Kindle. If you use the "fill storage" method to block updates, free some space before continuing.
Verify the location of all required folders and files on the Kindle.
Try copying the Update_KUALBooklet_hotfix_*_install.bin file to the root of your Kindle when connected to your computer, then go to Settings > Update Your Kindle and resume from step 5 in the Kindle Mod Wiki guide.
You can also just install using peki if you have issues with MRPI

Install KUAL