You need 3.2.8 firmware.. Use last bluespark twrp 3.1.1, camera quality is oxy whitout 1080 60fps, good battery life, dual app work on xs build
To have all notifications whitout problems u need to set as well the optimization of the app u need instant notification and the automatic start permissions..
Using dual sim, only problem ( that I've found) is that u can't disable secondary sim.
Coming from other Rom,other firmware etc need to clean flash,also data, specially if u are using magisk as root manager.
For my personal experience is one of the most stable Rom for op3,most stable that the last ob.
Good combination battery performance is miui whit boeffla anykernel for oos 3.x.x(you can find it on boeffla.de).
As gapp use the battlehero zip because gapp need to be installed as a system app to work,here the link:
https://www.androidfilehost.com/?fid=745425885120738046
After clean all partition I flash in order :
Rom
Gapp
Magisk
Xposed
Kernel
No issues.. Hope this can help people who want to try miui on op3