[General Questions and Answers] witty_bricker:
First of all, before you read my guide below, how much knowledge do you have so far? Is your bootloader unlocked? That is the hardest part. If it's still locked, you have to either buy a code somewhere or use quite some effort, opening up your phone and do some tinkering. I will not go into details because I hope it's not necessary and you are already there :).

I successfully rooted my honor 9 (STF-L09) with magisk using the official guide and also a guide on the OpenKirin homepage that uses appropriate terminology and commands for Kirin devices. However, I had to do some things differently, because Magisk > v20.4 fails to install somehow.

I would love to know why the installation of higher versions fails and install Magisk v23.0, but I can only tell you how I installed v20.4. Hope you have ramdisk because it's a much better experience with Magisk. I had to do it on EMUI 9 before I downgraded, so do not upgrade to EMUI 9, you may lose ramdisk! I will try to explain the install from recovery with EMUI as good as I remember, but first the ramdisk way. As always, follow at your own risk! Can just confirm it worked on my phone!

Follow the official Magisk guide, but just until before you reach "Patching Images".

If you have ramdisk, got to the next step. Otherwise, read the guide about magisk from recovery and follow my explanation at the bottom afterwards.

Now that we have the necessary info, we need an older version of Magisk Manager to get v20.4 running. 7.5.1 is the latest Manager compatible with Magisk v20.4, but you are welcome to DYOR. Get Matrix Manager from the official Github releases.

Install Magisk Manager 7.5.1. Connect your phone and run adb install PATH_TO_MM_APK

To actually root the device with Magisk v20.4, we need to tell Magisk Manager to stfu about the outdated version and available updates. We can achieve this by modyfying the update channel in the settings to a custom channel. You can get the appropriate URL for the setting in this github repository. This is the appropriate commit. The link to the raw file is the following: https://raw.githubusercontent.com/t...5ffa9b079f3a411dd2c00a80a3d985ccc/stable.json. Copy the link to the raw stable.json and paste it in the settings of Magisk Manager as the custom channel URL. Restart Magisk Manager and verify it does not complain about the old version anymore.

Now Magisk Manager allows to actually patch the image. You should continue with the OpenKirin guide now. The official guide uses "boot" instead of "ramdisk", which is probably not appropriate for your device. But again, DYOR to make sure.

That should be it if you've got a ramdisk. If not, first read "Magisk in Recovery" in the official guide. Then continue with "Patching Images" and be careful to use "recovery" when both "recovery" and "boot" are mentioned. The OpenKirin guide does not include patching recovery.

AFAIK with EMUI 8 you should have a ramdisk. Had to use Magisk from recovery when I was on EMUI 9, which is why I'm glad I downgraded.

If anyone thinks I'm talking BS, I would love to know how to install higher versions of Magisk myself, or what could be the issue!