Suppress all global shortcuts including Meta

We have an application running in fullscreen that asks for a password to allow modifications and access to the desktop. Think of a kiosk like setup. Obviously Alt+Tab and other global shortcuts allow bypassing this easily.

I found that I can disable global shortcuts temporarily by using dbus

gdbus call --session --dest=org.kde.kglobalaccel --object-path=/kglobalaccel --method=org.kde.KGlobalAccel.blockGlobalShortcuts 'true'

unfortunately Meta is not handled via kglobalaccel but directly by kwin so this does not work for Meta (Application Launcher). Is there a way to disable this as well?

Having a window rule works (370146 – Window rule to block global shortcuts doesn't block meta)
but it feels kind of indirect to enable/disable shortcuts by modifying the window title.

Does KWin have a similar dbus interface?