Thanks guys for providing the links and helping others during the last months! Has been a journey again.
Apologies for not putting the download links in post 2. But due to the migration I am not able to edit them (post to long error).Hope you can find what you're looking for with the search tool.
See you next year 
Cheers
Samsung is currently testing and rolling out the OneUI 3.0 / Android 11 update.
This thread will be for sharing the Update.zip files (.bin files) and for help and tips.
This thread is for the OneUI 3.0 Beta for Exynos (International) only.
Link to the Snapdragon Thread:
https://xdaforums.com/galaxy-s20/how-to/oneui-3-0-beta-s20-ultra-beta-tread-t4143441
- Galaxy S20 (4G/5G) Exynos
- Galaxy S20+ (4G/5G) Exynos
- Galaxy S20 Ultra Exynos
Download links in 2nd comment.
How to install
Youtube video by SStech, also valid for S20 series.
Only difference is no bixby key to press.
ADB-method:
1. Download SDK platform tools from here
https://developer.android.com/studio/releases/platform-tools
2. Extract them on your desktop.
3. Inside the extracted folder put the update.zip
4. Inside this folder, holding left shift, right click the mouse and select "open command prompt here". The command prompt will open.
5. Shutdown the phone.
6. Holding power+volume up buttons, enter into recovery mode.
7. Select "update via ADB". (you scroll down using the volume buttons and select using the power button).
8. Connect the phone to the PC using original samsung USB cable.
9. In the command prompt run the following command:
./adb devices
10. Wait to see that the daemon has started and that your device is found.
11. If you device is found, run the following command:
./adb sideload update.zip
The update process will start. You will see a percentage counting. First it will verify, then patch etc. Do not move the cable, disconnect the phone or power off the PC.
Once the process is completed (it takes some time) the phone will boot itself, update the apps and log into your home screen.
SD-card method:
1. Download the bin file and rename it to update.zip (by going to file options in win10 you can select to view the file extensions. This makes the renaming process much easier and safer, and avoids renaming the file to update.zip.zip)
2. Copy it to the root directory of your SDcard.
3. Shut down your phone.
4. Hold simultaneously Power+volume up buttons to get into stock recovery.
5. Using your volume keys navigate to "update via SdCard" and press power button to select it.
6. Again using volume keys navigate to the file "update.zip" and press power button to select it.
7. Update will start. Leave it till it completes. It will take some time.
8. Phone will reboot by itself and load android.
Original Samsung Firmware
In case if you need to flash 2.5, you can use one of the below options.
Frija
https://xdaforums.com/s10-plus/how-to/tool-frija-samsung-firmware-downloader-t3910594
SamFw
samfw.com
Note: for now after installing the beta update it isn't possible to reboot in to recovery via the VolUP+power button.
You will have to use ADB for that: "./adb reboot recovery"
For reboot to Download mode use the following command: "./adb reboot download"
Installing via this way shouldn't trigger KNOX warranty void.
However: updating to Beta is your own choice, no one is responsible if anything goes wrong
How to capture
HTTP Canary app:
https://play.google.com/store/apps/details?id=com.guoshi.httpcanary
1. Load canary
2. Start the update download but don't pause it.
3. Go back to canary and start that and it will grab the link.
NOTE: after installing the update, CLEAR your cache by going into recovery (VolUP - Power)
If you're NOT officially registered via Samsung Members, you won't receive OTA: you'll have to update every time MANUALLY with above method!
The update.zip files are for Multi-CSC OXM only (so NOT for the South American countries which have Multi-CSC OWO or Multi-CSC OXB)
Thanks to
@henklbr for letting me copy the majority of his S10 beta threads plus being so active on this forum while not owning the S20 line anymore, the tips and help are appreciated.
