For your information, earlier this month Xiaomi launched the same device in China (it is Redmi Note 5 in China) with MIUI 9.5 based on Android 8.1 Oreo. Some owners of Redmi Note 5 Pro Global variant installed the build (MIUI V9.5.4.0.OEICNFA) on their device and found that it bring Project Treble compatibility to the device.
Project Treble is an Android Oreo feature that addresses slow software update schedule of handsets. This feature also enables users to flash AOSP GSI (Generic System Images) onto your Redmi Note 5 Pro. Android 8.1 Oreo based MIUI 9 Global Nightly builds is now available for download. FunkyHuawei.club leaked the build, which you can download and install on your Redmi Note 5 Pro. Tech-savvy owners of this device can install the build right now. The update brings Dual VoLTE, PIP (picture in picture), and various fixes features to the device. To install the leaked Android 8.1 MIUI 9 Nightly build on Redmi Note 5 Pro, bootloader must be unlocked and have latest version of TWRP recovery installed on the device. Interested users can download the leaked Oreo nightly build from here and flash on their Redmi Note 5 Pro via TWRP (source)
