If I lose my smartphone on which the electronic driving licence (eDL) mobile app is installed, do I need to report the loss or apply for a duplicate of eDL?

No.  If you lose your smartphone on which the electronic driving licence (eDL) mobile app is installed, you do not need to report the loss or apply for a duplicate eDL.  You only need to download the app onto your new smartphone and log in to the system to complete the identity authentication for obtaining your eDL.