A developer on XDA has ported Android Pie-based applications associated with the Samsung One UI to the Android Oreo that is currently officially available for the Samsung Galaxy S9, S9+ and Note 9.
You must root Galaxy S9/S9+ or Note 9, if you have that one. You cannot install the android one UI apps on unrooted device. Your android phone must be rooted. Some of them are ZRLF, most are ZRL5. All of the applications have day and night modes.
Again, keep in mind that you cannot install them as normal APK files. If you do this, you will get “app not installed” message for all applications. So, if you want to install them correctly, you must root your device and try again.
It supports both arm and arm64. All credits go to forgotten from xda-developers.