Note : By doing this, you know that you're gonna do a modification to your phone, and im not in any way, responsible for what happen after. Escape Route for if something wrong happen is provided, but YOU DO THIS ON YOUR OWN RISK
since this phone is fairly new, at this moment a clear rooting method haven't established yet. This is what this thread for.
Based on information gathered from P20 Lite Forum (the rooting guide for that device even already up - here), it seems the old trick of rooting (from Mate 10 Pro) using Patched Boot Method is working fine. And Magisk is working
Basically this method need few pre-requisites :
1. Unlocked Bootloader (by getting the code here ) - and if you not sure how to do it, go here for the guide
2. Stock Boot (or RAMDISK to be precise for this phone) - I managed to extract it from 184.108.40.206 ROM version for CLT-L29 (download here)
3. Magisk Manager 5.5.4 (from Magisk Thread) to patch the .img above, or
4. Patched RAMDISK image (i patched it) from here
5. and of course computer with ADB & Fastboot installed (make sure you have latest SDK to prevent something not working)
Now, to Root it, all you need to do is,
1. Boot into bootloader
fastboot flash ramdisk patched_boot.img
4. You now should have root access, download Magisk Manager to manage modules and superuser
(you might need to flash this module if you failed to pass safetynet)
In case something go wrong, flash back the stock RAMDISK from pre-requistes number 2 above using same method as what u did to flash the patched one.