Nokia 2 is HMD’s only phone still officially running Android Nougat. In short, the 2 is problematic because it comes with low end hardware and with regular Android instead of Android Go. There is no way to update a regular Android phone to Android GO, so HMD is taking parts of Android 8.1 GO and optimizing it for Nokia 2.
The process of Android 8.1 beta testing started on 19th June, and is still going strong with a new update released today. The update is 1354MB in size, comes with October security patch and carries the version number V1.15P.
As we can see, it takes a lot of time to make the Nokia 2 ready for Android 8.1. The Nokia 1 and Nokia 2.1 that use Android Go are really nice devices that might serve well to extra light users, so it will be interesting to see what will the 2 look like after the update.
The official release date of stable Android 8.1 for Nokia 2 is unknown.