In theory, this guide will work on every variant of Nokia 6, but you can only use CN Variant ROM.
Update: Until Jan 25th 2019, D1C-612H-0-00CN-B03 (Feb 2019 Update) was the latest release of Nokia 6 2017.
I strongly recommend you to unlock the bootloader before proceed - I won't tell how to unlock the bootloader in this guide.
Take a look to this video first if you want to know the experience of Android Pie: https://youtu.be/izt650UNB5Y
In this guide, I'll provide two different methods to get Android Pie on your Nokia 6.
Both methods will erase your userdata.
Here's an important hint: Nokia 5 (ND1) and Nokia 6 (D1C or PLE) can flash each other's stock firmware, including TA-1000 Chinese firmware.
If you're eager to experience Global Android Pie on your Nokia 6, you can read this guide: https://forum.xda-developers.com/nokia-5/how-to/guide-how-to-install-android-pie-build-t3883901
Method 1: Use OST LA to flash my homebrew firmware
You should be familiar with this method.
1. Download "D1C-612H-0-00CN-B03_Homebrew.7z" from following site:
Note: If you can't extract it correctly, please use 7-Zip ZStandard (not Original 7-Zip) to extract.
2. If you have Android 8.x running with LOCKED bootloader, please downgrade bootloader back before processing. If you have unlocked bootloader, you needn't to downgrade the bootloader.
If you're not using TA-1000, you need to change SKUID to 600CN by following this guide: https://forum.xda-developers.com/nokia-7-plus/how-to/guide-how-to-change-skuid-to-worldwide-t3808520
3. Open OST LA or NOST and load the mlf file, in download options, only choose "Normal Download" and "Erase userdata".
If your phone boots suddenly when flashing splash, close OST LA and force power off your phone then flash again.
You can download NOST from https://github.com/StollD/NOST
4. All done, enjoy Android Pie.
Method 2: Force OTA Update
1. Download the package "D1C-612H-0-00CN-B03-update.zip" from here:
Or this for Global Android Pie, rename it to "D1C-612H-0-00WW-B03-update.zip":
2. If you're not using TA-1000 or 1003, rename the package to PLE-612H-0-00WW-B03-update.zip
3. Skip this step if you're using TA-1000.
Non TA-1000 users need to change SKUID to 600CN by following this guide: https://forum.xda-developers.com/nokia-7-plus/how-to/guide-how-to-change-skuid-to-worldwide-t3808520
4. Place the package to root directory of internal storage.
5. Dial *#*#874#*#* to update.
6. After update installed, it
7. Enjoy Android Pie.
Q1: Can I root it?
A1: Yes, but you must have unlocked bootloader, and TWRP is unusable. Also, Magisk 18 is unusable.
Q2: How to downgrade bootloader in case I want to roll back without unlocked bootloader?
A2: Rename existing Android 8.0 OTA package for your model to D1C-9999-0-00CN-B09-update.zip. Then you should know what to do next.
Android 8.0 for TA-1000 DL: https://ota-filesite.c2dms.com/SWImage/500000772 (DO NOT USE IT ON NON TA-1000! )
Q3: My language is unavailable!
A3: Please follow this guide: https://hikaricalyx.com/2018/09/21/how-to-change-your-nokia-phone-language-to-japanese-or-korean/
Q4: Where is Google Play Store?
A4: You need to download Play Store APK manually from websites like Apkpure and install it manually.
Q5: I heard both TA-1000 and TA-1003 doesn't have NFC feature. Will I lose NFC if I installed this build?
A5: Nope, you can still use NFC.
Q6: When will you unlock Nokia X7 / Nokia 8.1?
A6: I don't know!
Q7: When will you get Nokia 9 Penta Camera Phone?
A7: I don't know, don't ask.