HMD will provide PIE update for all devices in phases but the thing is to ensure that beta build should run with less bugs thats why. but it is not recommended to unlock bootloader and force update your mobile as chinese variants are different platform than global variants.Instead of doing this wait for announcement of pie beta build as they have provided pie for 5.1+,6.1,6.1+,7.1,7+,8,8.1 only nokia 5,5.1,6,8 Sirocco are only device to receive pie updates
Answers
https://forum.xda-developers.com/nokia-6/how-to/guide-how-to-install-android-pie-build-t3879899
https//youtu.be/eO4t8n8TyA0
but it is not recommended to unlock bootloader and force update your mobile as chinese variants are different platform than global variants.Instead of doing this wait for announcement of pie beta build as they have provided pie for 5.1+,6.1,6.1+,7.1,7+,8,8.1 only nokia 5,5.1,6,8 Sirocco are only device to receive pie updates