Contrary to speculation claiming that the device would be left on Android Oreo, ASUS has confirmed that the ROG Phone will still receive Android 9.0 Pie. The company has stated when it will bring the OS upgrade to the ZS600KL too, although the ZenFone 4 has not been given such a reprieve.
https://www.notebookcheck.net/ASUS-backtracks-on-stance-ASUS-ROG-Phone-to-receive-Android-9-0-Pie-update-after-all.440644.0.html
Asus is a joke, end of Nov, they will say delay again to 2020.