Well you would be using a Samsung Tool (Odin) to Flash the Samsung Firmware - Worst case scenario - Odin would simply fail to Flash - Best case scenario - You would have successfully installed One UI Pie on your device 🐧
Well - All the Canadian devices use the same Firmware - So it wouldn't really matter if you Flashed Bell - Rogers or Telus for example AND the latest versions are all the same.. So if you downloaded the Bell or Rogers Firmware it doesn't make any difference - Especially since I don't know what Carrier's Software Version is installed on your device?
Have you contacted your Carrier in Tunisia & asked them about the One UI update?
To install the Firmware with Odin - You need to Download the Firmware to your computer - Extract it & you'll have 5 Md5 tar files:
BL AP CP CSC HOME_CSC
You copy the respective files to the correct slots in Odin - I'm pretty sure since I don't see any Firmware for your Country - That you should select CSC & NOT HOME_CSC for the CSC slot...
In the options in Odin - You should ONLY have Reset-Time & Auto Reboot selected - DO NOT SELECT REPARTITION!!
Boot into Download Mode - Connect your phone to the computer & Wait for the Blue box showing that you are connected & click on Start.. There's plenty of YouTube videos on how to Flash Samsung Firmware with Odin - You SHOULD watch a couple several times BEFORE you start 🐧
Well like I said - If Flashing the Firmware is successful - Then it will update your device from Oreo to One UI Pie - So yes.
What I would do if I was in your position is - I'd back my device with Smart Switch & Google / Samsung & Factory Reset - Boot into Download Mode (Power Off - Press & Hold Power + Bixby + Volume DOWN until you feel the phone vibrate - Release ALL Three - The phone will Boot to a pail blue screen with a Warning - which is normal - And follow the steps posted previously 🐧
Because it's the Carriers who release the updates - By the way - The only way that I see your posts is by going to this thread & looking - I don't get notified that you posted an additional question - Unless you Tag me or Click on the "reply" button 😉