I need some program for unexperienced users who use Debian, so that they are asked to update the system from time to time using the GUI. I know that there is update-manager for Ubuntu, but they use Debian. Is there any alternative or an easy way to install update-manager on Debian?
package-update-indicator might be enough for you.
sudo apt install package-update-indicator pk-update-iconSynaptic would be an more in-depth alternative with more gimmicks. Countless other managers are mentioned here.