Magisk and SU are root method. The difference is that magisk is systemless and dont change your boot.img
Be careful of which apps you uninstall, you need some chinese apps to make everything working fine. So keep that in mind.
Hm.. Maybe.. Idk what you did
Add google contacts and google sync to Security autostart white list and open google contacts after that.
Some apps wont work if they find out that you are rooted, that will happen if you flash SU. So use magisk to hide root.
But if you dont care, then flash SU