Now it seems that the Android 7.1.2 Nougat Software update would be coming soon to the Nokia 6.
According to GFXBench, HMD has started working on Android 7.1.2 Nougat updates for the Nokia 6 (TA-1000, TA-1003, TA-1021, TA-1025, TA-1033, TA-1039).
Android 7.1.2 is an incremental maintenance release focused on refinements, which includes bugfixes, optimizations, and a small number of enhancements for carriers and users. Along with these enhancements, it also brings new gesture 'Swipe fingerprint scanner to open notification'.
That said, there's no exact date on when HMD will be rolling out Android 7.1.2 Nougat for the Nokia 6. We will let you know once the update is out.
HMD recently announced that all the Nokia Android Smartphones inducing the Nokia 6 will be updated to Android 8.0 Oreo by the end of 2017.