Android 12 also arrives on Samsung Galaxy S9/S9+ and Note 9 with this ROM - Real Mi Central
S9+ Rom Port For Galaxy S8 & S8 Plus - YouTube
Galaxy S9 Android 8.1 Oreo Update, LineageOS 15.1 AOSP ROM Download Now Available | Redmond Pie
Samsung Galaxy S9 and Galaxy S9+ can now boot official TWRP
List of Best Custom ROM for Galaxy S9 and S9 Plus [Updated]
This is Noble rom, an android 12 custom rom for the Galaxy Note 9 and S9 by AlexisXDA on XDA. It has some bugs but nothing that's deal breaker, some stuff have
Custom ROM brings One UI 4.1 to Galaxy S9 and Note 9
Thanks to treble, Galaxy S9 gets AOSP ROM based on Android 8.1 already
Download and Install crDroid OS on Samsung S9+ Exynos [Android 10]
Pushing S9 battery to the limits [Custom ROM + Root] : r/GalaxyS9
10 Best Custom ROMs for the Samsung Galaxy S9 - TechSamaritan.com
Samsung Galaxy S9 ROM Port for Galaxy S8 and S8+ | Install S9 Oreo ROM on S8