HMD Global has a dedicated section on the official Nokia.com pages about monthly security updates for Nokia Android devices. That section was there for quite some time, but HMD recently made it much more readable by adding the unique software builds each device has depending on the market, which allows users to track when an update becomes available for their device.
Something similar, but much more detailed, we had with Lumia device during the WP8 era and Lumia Amber, Black, Cyan and other updates. HMD’s watchlist doesn’t show devices running the Android Oreo beta program and only mentions security update availability. Keep in mind, when HMD releases an update, there is a process to be done behind it until the update reaches the customer, so delays of 1, 2 or more days are frequent.
You can check HMD’s Nokia Smartphone Security Maintenance Release Summary here.