The flagship Nokia 9 PureView has started receiving the September 2019 Android Security patch. The update just brings the security patch for the month of September and is 73.4MB in size.
The updates are rolled out in phases so might not be available for download in all markets. You can manually check for the update to see if the update is available for your Nokia 9 PureView in your region. The update has been rolled out in Russia, India and some European countries. You can learn more about Android Security updates by visiting the Android Security Bulletin.