[Lenovo Legion Y700] switchem:
Alright, I read through your helpful posts again, as well as a few other links, and I think I'm putting the pieces together (maybe, lol)...

The following is my basic (possibly incorrect) understanding of the process for rooting the 2023 Y700. Others, please don't follow this is a guide if you're new to this. And, if anyone does see something incorrect, please let me know! I'm posting this for feedback/help and for future reference.

The high-level process (WIP. I'm learning. Please correct me on any inaccurate info!):​

To root the device with Magisk, we need to patch the boot.img. However, we don't have access to that if we're not rooted, so it must be extracted from a stock rom or a full OTA update, not an incremental update. In the case of the Y700, this will be between 3 and 5 GB in size. A stock rom can be created with a little work (like this guy did: https://note.com/calm_hebe587/n/nae1c964b45bc) or you can download one if there's one available on the internet (like the one that person made and shared here: https://sourceforge.net/projects/y700-tb320fc/files/).

With a full stock rom in hand, we now need to extract boot.img so it can be patched with Magisk. Again, these pre-patched can often be found online, but if there isn't one available, it can be extracted from the ROM with a tool like payload-dumper-go (https://github.com/ssut/payload-dumper-go). EDIT: It seems the sourceforge download linked in the previous paragraph, when unizpped, has a folder called "images" which contains boot.img already, so we can use that and go to the next part of the process...

Next, we need to patch boot.img with Magisk. Install Magisk from github (https://github.com/topjohnwu/Magisk/releases). Put boot.img somewhere on your device, open Magisk > Install > Select and Patch a File. Transfer that patched file to your computer for the next part of the process.

Finally, reboot into bootloader. Over adb, run `fastboot boot path-to/magisk-patched-file.img`. When done, run `fastboot reboot`. When rebooted, go into the magisk app to confirm it worked.

The bootloader can be re-locked, but be aware of the "Rollback Protection" on Android that might prevent the device from booting with a "Your device is corrupt" error (more info: https://note.com/calm_hebe587/n/n8365967515bd). My device came sealed with 15.0.654, and I think(?) I'll be okay updating via OTA to 15.0.677, rooting, and re-locking the bootloader. We'll find out, lol.

I was wrong. I got stuck in a boot loop after re-locking, and had to flash the full rom to fix it. I rooted again, and tried re-locking again, and got the "Your device is corrupt error.

To those that are knowledgeable, does this sound correct?

The Steps (I can confirm this worked for me):​

*NOTE: My device – Y700 2023 model TB-320FC – came sealed with ZUI 15.0.654 installed. I updated via OTA to 15.0.677 before performing the following steps. I don't know if or how much that matters, but wanted to note it.*

UNLOCK YOUR BOOTLOADER BEFORE DOING THESE STEPS (WARNING: UNLOCKING WILL WIPE YOUR DEVICE).

1. Download the stock ROM from https://sourceforge.net/projects/y700-tb320fc/files/. I downloaded "y700_TB320FC_zui_15.0.677_fastboot_rom.7z", and when unzipped, it contained a file called boot.img.

2. Connect the device to your computer via USB using the port on the long side of the device. Confirm the ADB connection by running the command `adb devices`.

3. Transfer boot.img to the device via adb (eg. `adb push boot.img /sdcard`) or any other means.

4. Install Magisk with the APK from their from github (https://github.com/topjohnwu/Magisk/releases).

5. Open the Magisk app and click "install". Choose "Select and Patch a File", and navigate to the boot.img file that you put on the device in step 3. Click "Let's Go". Magisk will patch the boot image and save a new files called something like `magisk_patched-26400_drwZp.img`, probably to your downloads folder.

6. Copy the patched magisk file to your computer via adb (eg. `adb pull /sdcard/download/magisk_patched-26400_drwZp.img`) or any other means.

7. Reboot to bootloader via ADB command: `adb reboot bootloader`

8. In Fastboot mode, confirm a proper connection by running the command on your computer: `fastboot devices`. You should see your device listed.

9. Flash the patched boot img. Eg. `fastboot flash boot /path-to/magisk_patched-26400_drwZp.img`. You should get the message "Finished. Total Time..."

10. Reboot device: `fastboot reboot`

11. A Magisk app icon should automatically appear in your apps, and if so, you know it worked. Open the Magisk app and confirm it worked.

12. Open the Magisk app. It will prompt you to download and install the full Magisk app to finish the setup. Click OK.

13. You'll be prompted with a "Requires Additional Setup". Click OK to proceed and the device will automatically reboot.

14. Open the Magisk app and it should read "Installed: 26.4 (26400)" or something similar. Congrats! You've successfully rooted the device!

15. However...if you install Netlfix, you'll notice it doesn't work. It will immediately throw an error "Sorry...15001". This is because the bootloader is unlocked (read more about it here: https://smartasw.com/archives/17857#index_id9). We need to re-lock it for it to work...

...BUT I tried re-locking the bootloader, but after that, the device wouldn't boot. It would only boot loop to the logo a few times, and then only into fastboot mode. EDIT: I fixed the boot loop by flashing the full ROM using the flash_all.bat from the sourceforge download. After that, I was able to root the device again with the steps above.