The latest update weighs in at around 149 MB and features the latest security patch. You won't get new features or improvements with this update.
The Nokia 6 is available only in three markets i.e. China, Hong Kong, and Taiwan. HMD plans to make all the three Nokia Android phones available in most of the countries by July 2017.
Recently HMD promised that the Nokia 3, Nokia 5 and Nokia 6 will be getting software updates for till next 2 years. That means, the Nokia 6 and other two devices will be getting Android O for sure.