You can set Smart Launcher as default launcher on your Oppo device without rooting or using advanced tools. The option is already available in the system settings, it’s just a little hidden and unfortunately, Oppo prevents the launcher to help the user to find its location.
Install Smart Launcher then follow this 4-steps procedure.
(Tested on Oppo Reno, Oppo RealMe 1, Oppo F7, Oppo A57, Oppo A83, Oppo A37, Oppo A71, Oppo F5, Oppo F3, OPPO F3 Plus)
You should now be able to enjoy your favorite launcher on your Oppo device!
Appearantly some Oppo devices are just incompatible with third party launchers. If this is the case, it means you won't be able to use Smart Launcher or any other launcher on your device.
At the moment, there aren’t any other known issues on Oppo device, if you find any, please report the problem to firstname.lastname@example.org