The Kubuntu is using the KDE desktop. The KDE and its applications are saving the global shortcuts to the ~/.kde/share/config/kglobalshortcutsrc .
The kglobalshortcutsrc is a text file.

As mentioned there is a gui: KDE system settings> Shortcuts and Gestures...
But the kglobalshortcutsrc can be edited with the text editors & scripts.

More: KDE Forums - Load Global Keyboard Shortcuts from a backup file: https://forum.kde.org/viewtopic.php?f=66&t=94403
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