[OnePlus 6 Guides, News, & Discussion] kyljys:
I have successfully degoogled and debloated the latest OOS (atm 10.3.8) and have a working microg setup using nanodroid package. Battery life is nice. 45hrs with 10,5hrs SOT on the first go! Not any unwanted background data moving, success I'd say! So for anyone interested, here are roughly the steps I took.

I couldn't deodex the services.jar with VdexExtractor so I used FakeGapps from Edxposed. Works!

In following guide we will first get a factory state OOS with twrp and root WITHOUT internet. Then we uninstall system app 'android setup', allow internet, get Edxposed working and FakeGapps installed. Then we install Nanodroid package from twrp to get a working microg and setup it and debloat. + Disable trackers using App Manager from F-droid repositories or github. Get it ready for sideloading or use adb. Support the developer!

General guide (everything gets erased):

1. Pure factory installment using MSM tool for 10.3.8 from Oneplus 6 unbrick tools. (XDA forum)

2. The phone starts, go through the initial setup bypassing everything you can. DON'T SETUP ANY WIFI!

3. Immediately switch off mobile data from quick settings, just in case. We dont want android setup to update any apps.

4. Enable unlocking the phone, reboot to bootloader

5. Unlock the bootloader (fastboot oem unlock)

6. Do parts 2 and 3 again (choose Oneplus slate font at this time if you ever want it to work)

7. Enable USB debugging, connect to computer, check 'adb devices' to get the window to allow the computer to appear. (The daemon needs to be running)

This all was to get the phone into pure factory state without automated changes, bootloader unlocked and adb working.

8. Install twrp and magisk. Boot up the phone.

9. Remember! No internet connections yet! Uninstall the system app 'Android Setup'. I used sideloaded AppManager for that. You'll know when you have uninstalled the correct app when the notification of android setup disappears.

10. Reboot

11. Now you can connect to internet.

12. In magisk, install Riru core, (mandatory reboot here!) and Riru Edxposed (2nd reboot)

13. In Edxposed, install FakeGapps and activate it. Reboot.

13. Now you can connect to internet.

This was all done to setup the phone for Nanodroid package and get safely to internet without unwanted updates.

14. Download a nanodroid package from github. I used just the microg version. Flash it from twrp. It should debloat some necessary google stuff, install aurorastore and aurora services and straight up working microg.

15. Check if microg is working and do registrations and enable cloud and location stuff. Reboot.

16. Install any app that uses google cloud service for push notifications and check from microg settings that it shows in the list. Don't continue installing any such apps until it does. Reboot or troubleshoot if necessary with microg related info.

17. Back up current setup from twrp for fallback.

18. Debloat to your heart content, except only disable and force stop the play store. In my case the app is still the official one. Don't use.

19. From AppManager, run disable all trackers, including system apps from 1-click ops.

There! Use some time, and if everything is to your liking, make a backup. Remember to disable trackers from every app you install after you have configured it.

Sidenote: Aurora store did not work when installed systemlessly, but worked fine as a user app