The 2018 refresh of the Nokia 6 was released in China earlier this month, but it strangely still ran Android 7.1.1 Nougat out of the box. The Nokia 7 was introduced in October, but like the new Nokia 6, it's only available in the Chinese market at the moment. Now both phones are receiving an update to Android 8.0 Oreo.
It's understandable that the Nokia 7 launched with Nougat, considering the software was likely being finalized when Oreo was released. The new Nokia 6 launching with Android 7.1 is more bizarre, especially considering it now has Oreo just 15 days after it went on sale.
There's a popular theory that some OEMs are purposely avoiding shipping phones with Oreo, so the company doesn't have to support Project Treble, but it's difficult to definitively prove that. Either way, at least the new Nokia 6 will have Oreo by the time it's released internationally.