[OnePlus Nord N20 5G] PsYk0n4uT:
Hello, I just wanted to post this as an answer to many questions regarding not being able to use DSU to install a GSI for testing or gaining root.

The DSU install in developer options is NOT what we are using for installing GSI's temporarily for pulling boot images. And wont work for that.

You can use DSU sideloader to install GSI's tempoarily or use the sticky feature to make it semi-permanent. but if you plan on using the GSI long term make sure to set your userdata to a reasonable size because your gonna want to install apps and download things. take note that if you dont use the sticky feature, once you reboot the phone it goes back to your regular stock OS or whatever you were running on before and you lose everything in the GSI that you havent saved to external media/sdcard/cloud. If you use the sticky feature you can reboot the phone and retain the GSI installation.

*This is NOT mine and i take absolutely NO credit for it and am just providing it here to make it easy to find for other N20 users and newcomers looking to pull their boot images to patch with magisk and root OR for testing GSI's.

If you want a permanent GSI install you will need to flash. BUT that being said, i have used the sticky feature to stay in a GSI for a few weeks. Definitely gonna want to set that user data pretty high if you wanna stay in one long term. This isnt the best way to install a GSI if you plan on staying in it permanently but it would work if you want to keep your stock installed in case of system failure for some reason.... Best to pull a FULL system backup while in a rooted GSI and save it to your PC or in the cloud.........PLEASE make that your #1 priority once you get root because NOBODY can help you restore your EFS partitions should you screw those up. They contain your IMEI and device-specific info that you cant get ANYWHERE else and NEVER will be able to either.

My suggestion is to install a prerooted GSI, then use Partitions Backup & restore app found here https://www.apkmirror.com/apk/wanam/partitions-backup/ or on playstore and change options to save the backups as RAW (.img) then open the folder their saved to /storage/emulated/0/Partitions Backups/ and use zarchiver or any other compression tool to compress them all into a single archive to save some space and make them easier to manage and/or upload....... (you may want to change screen timeout/'turn off display after' in android settings to 30 mins to keep the screen from turning off while you do your backup because it takes a while (your stock full backup will be about12gb after all the .img's are compressed)...

Now heres where you can find DSU sideloader and also a copy/paste from the github page:

GitHub - VegaBobo/DSU-Sideloader: A simple app made to help users easily install GSIs via DSU's Android feature.

A simple app made to help users easily install GSIs via DSU's Android feature. - VegaBobo/DSU-Sideloader

github.com

DSU Sideloader​

A simple app made to help users easily install GSIs via DSU's Android feature.

Requirements​

Android 10 or higher

Unlocked Bootloader

Device with Dynamic Partitions

A GSI you want to use!

Community GSIs: https://github.com/phhusson/treble_experimentations/wiki/Generic-System-Image-(GSI)-list

Google GSIs: https://developer.android.com/topic/generic-system-image/releases

*Remember to use GSIs compatible with your architeture, vndk implementation..

You don't need root to use this app, however, running on non-rooted devices, requires adb (you will be prompted to run a shell script to invoke DSU installation activity)

Rooted devices via Magisk, should be running Magisk v24 or higher, older versions may break DSU feature.

We highly recommend using this app with Stock ROM, Custom ROMs aren't supported.

How to use?​

Install app

When opening for the first time, you need to give read/write permission to a folder, create a new folder and allow access

*this folder will be used to store temporary files, like extracted GSIs from compressed files)

Select a GSI to install

*accepted formats are: gz, xz and img

You can customize installation as you want

*like changing userdata size for dynamic system

*changing gsi file size is not recommended (let app do it automatically)

Tap on "Install GSI via DSU"

Wait until finishes! (it may take a some time)

Once it finishes, next step may vary:

On rooted devices, DSU screen will appear, prompting you to confirm installation, after that, check your notifications, DSU should start installing GSI

On non-rooted devices, you will be prompted to run a command in adb, once you run, DSU screen will appear asking you to confirm installation, after that, DSU should start installing GSI

Once dynamic system is ready, you can boot it through notifications

Other information​

DSU feature may be broken in some ROMs.

gsid does not let you install GSIs via DSU when you have less than 40% of free storage.

gsid checks if selected GSI size is multiple of 512 (preventing corrupted system images).

If you have disabled/debloated system apps, make sure "Dynamic System Updates" app is not disabled.

To use "ADB mode" on rooted device, deny root permission.

About DSU​

DSU (Dynamic System Updates), is a feature introduced on Android 10, that let developers boot GSIs without touching current system partition, this is done by creating new partitions to hold a GSI and a separated userdata, to boot on them when desired.

Unfortunelly, DSU depends on Dynamic Partitions (your device need to support, otherwise, won't work), and most GSIs requires unlocked bootloader to get them booting properly (since only OEM-Signed GSIs are allowed to boot on locked bootloader).

GSIs can be installed via DSU without root access, using ADB, running some commands, you can read more about installation process here: https://developer.android.com/topic/dsu

Once installation finishes, Android creates a persistent notification allowing you to boot into "Dynamic System" (GSI installed via DSU), and you can boot into installed GSI, without touching your system partition, or breaking the "real userdata" partition.

After booting Dynamic System, you can try and test whatever you want, when you need to switch back to device's original system image, everything you need to do, is just, a simple reboot!

When doing a long test, that may requires lots of reboots, this can be a pain, however, is possible to enable "sticky mode", that enforces dynamic system, instead of device's original system image, once tests are done, you can disable sticky mode and return to original system image.

That is basically a quickly explanation about DSU, a amazing feature, like a "dual-boot" solution, limited, however, very safe (since no read-only partition will be modified, and if GSI does not boot, just a simple reboot will return you to the original device's system image).

You can read more about DSU here: https://source.android.com/devices/tech/ota/dynamic-system-updates

How to enable Sticky Mode?​

Reboot to Dynamic System, and:

use this command on adb: adb shell gsi_tool enable

or from local adb shell: gsi_tool enable

or from local rooted shell (eg. Termux on rooted GSI): su -c 'gsi_tool enable'

When sticky mode is enabled, device will always boot into dynamic system, instead of device's original system image.

To disable, use the same command, instead of enable , use disable

****Special Thanks To VegaBobo for this awesome app to make this a simple process And to AndyYan for the suggestion!!***

DSU Sideloader GitHub main:

GitHub - VegaBobo/DSU-Sideloader: A simple app made to help users easily install GSIs via DSU's Android feature.

A simple app made to help users easily install GSIs via DSU's Android feature. - VegaBobo/DSU-Sideloader

github.com

DSU Sideloader Github Releases(downloads) [**Most will want to use the app-release.apk NOT app-debug.apk**]:

Releases · VegaBobo/DSU-Sideloader

A simple app made to help users easily install GSIs via DSU's Android feature. - VegaBobo/DSU-Sideloader

github.com

Partitions Backup & Restore:

Download Partitions Backup & Restore APKs for Android - APKMirror

Download Partitions Backup & Restore APKs for Android - APKMirror Free and safe Android APK downloads

www.apkmirror.com

or on playstore at https://play.google.com/store/apps/details?id=ma.wanam.partitions

Please consider donating to the developers who work hard and spend their valuable time to provide these awesome apps/mods that bring joy to your life!

****Special Thanks To VegaBobo for this awesome app to make this a simple process And to AndyYan for the suggestion and time spent on mods/ROMs!!***

Also shout out to Wanam for this awesome backup tool thats STILL relevant and working as great as ever.

11/11/2022: received response from developer about the issues with DSU sideloader failing