The extension https://github.com/stefanwalther/sense-extension-governance is unfortunately outdated and was not possible to import in a new Qlik Sense system.
In the telemetry app I couldn´t find anything about extensions.
In the meanwhile I decided to use another aproach:
Create a security rule to hide apps flagged with certain custom properties. If users a complaining that an extension is missing, I can change the custom property to re-activate it if necessary.
