The restore method looks promising. I shall download it and look at the *.bat to see where I can hook up into the process.
The branded/unbranded thing is probably a SIMlock to a carrier, it makes sense that this cannot be broken through a stock ROM. My phone has no such limitation so it should not be a problem.
unbranded phones, and I’m not sure
I would use branded loosely in those circumstances to describe “Carrier branded” - I see no real references to that and any locks. This would be an example of a branded phone https://www.pocket-lint.com/phones/news/oneplus/157327-oneplus-nord-n200-release-t-mobile-specs but I cannot tell if that is what he refers to. Just my two cents, but @chrisrg’s path seems safe: or I might ask the author on the thread before committing.
That sounds good.
I take it you are on Windows then? If so, you should have no trouble flashing one of those roms. It’s quite straight forward.
Easy on linux too, just might need to make your own shell script.
After restoring, remember to set usb debugging again.
I can tell you from experience, it might be a long wait! 
And eOS will have the R build out by then anyway
The flash-all.bat looks kind of scary, it flashes 27 images, some of them with --disable-verify.
I am on MacOS and would go through the list manually, avoiding to port a batch file to bash.
About the R build: assuming there was one, could I use it to downgrade to Q or would I be stuck there?
Before I start: do you think stock flashing is my best option? Any last words or warnings?
[RECOVERY][3.4.0-13][avicii]Unofficial TWRP for OnePlus Nord (Testing) | XDA Forums
[RECOVERY][UNOFFICIAL] OrangeFox Recovery Project [avicii][OnePlus Nord] | XDA Forums
When the R build for eOS is released, as yet no hint of an eta, the phone would have to be restored to stock android 10 (just like you are about to do now) before installing eOS-r
Yes, I do. I would do exactly as the xda thread says, boot up when finished, set usb debugging then carry on install eOS.
Or you could put the phone in a drawer and wait for eOS-r to come out and flash it from it’s present state.
It could be keeping your actual android 11 firmware, only replace /vendor.img, by an android 10 based. and install /e/Q,
in a near futur, you will be able to only replace the /vendor.img by the android 11 based one,
and install the /e/R build skipping the entire reinstall of the android 11 stock firmware step.
Replacing /vendor, could be done by Fastboot or by TWRP or OrangeFox Recovery previously linked (if they works…)
Just researching the use of “Unbranded” by @mauronofrio Recognized Developer at xda. He also wrote [OnePlus 6] How to rebrand your device: from HydrogenOS to OxygenOS and vice versa | XDA Forums and OnePlus 6/6T: How To Rebrand from HydrogenOS to OxygenOS
In preparation to flashing to Android 10 I rebooted the device and lo! /e/ came up, much to my surprise. To make sure everything is in order I would like to get your opinion on this. Here is what happened:
Questions:
Great news! Go to Settings > About phone > Android version > tap for /e/ version, long press copy to clipboard.
Also foot of About phone > Build number. Also, long press copy to clipboard.
Great news indeed!
It’s Android 10.
Build number: 10 QQ3A. 200805.001 eng.root.20211027.184332 dev-keys,stable-release
Probably I did not upgrade to R, although this seems not very likely.
I am amazed that formatting /after/ flashing did the trick.
Thanks a ton for your help!
@Manoj Hi, better provide no installation instruction than a wrong one. Can you please update the instruction or at least write on top that it’s wrong!!!
I guess point 6 is the TWRP recovery?
Hours later: found an inofficial TWRP, wipe was ok, but advanced wipe has no cache and system option? I have only the following options:
Dalvik/Art Cache
Data
Internal Storage
USB Storage
Isn’t there a way to do this with fastboot commands instead of TWRP?
C:\fastb>fastboot erase cache
Erasing ‘cache’ FAILED (remote: ‘Check device console.’)
Same with system and nothing on console
Hi, I’ve just gone through the steps for the OnePlus Nord - “avicii”.
When starting the phone, I am getting an error stating that the OEM is unlocked.
I tried to lock it again and received an error:
Your device is corrupt. It can’t be trusted and will not boot. Visit this link on another device: g.co/ABH
The device was working perfectly aside from the OEM warning before locking the bootloader.
Is there a step missing in the instructions to lock the bootloader again?
Hi @wadejbeckett welcome to the /e/ forum. Sorry if you do not get a helpful response on this thread. Locking after /e/ install is not possible on this device, I think!
Sadly, many devices get that annoying message - some just regard this as a “badge” for “escaping”!
This does not help you right now 
If you do not get a solution feel free to ask on a new thread.
Hello! the picture from Info about OnePlus Nord - avicii suggests it has one fron camera when in reality it has two, I might we wrong but seems like that 