It was only a few days ago that Google pushed the stable Android 11 update to its Pixel phones and uploaded the source code for the release to AOSP, but a developer on XDA has already cooked up the first Android 11 custom ROM to be released on our forums.

XDA Member abhishek987 built a pure Android 11-based AOSP ROM for the Redmi K20 Pro/Mi 9T Pro. The ROM is nearly fully functional, with all basic hardware features such as Wi-Fi, Bluetooth, camera (photo and video), audio, sensors, LED, GNSS, and most importantly, RIL (for calls, SMS, data, VoLTE) working. The only issue with this build is that SELinux is set to permissive, which admittedly has serious security implications. This preliminary build is not meant for daily use, though, so you're better off not installing it unless you're okay with running a less secure software build that could have bugs not foreseen by the developer.

Redmi K20 Pro / Xiaomi Mi 9T Pro Forums

Since Google announced Project Treble alongside Android 8.0 Oreo, Android has become more and more modularized, making custom ROMs closer and closer to Generic System Images, or GSIs. XDA Recognized Developer phhusson tells me that Google's Android 11-based GSI can boot on most Qualcomm Snapdragon devices that launched with Android 9 Pie or Android 10, provided a few changes are made for vendor compatibility. We've come a long way from the days when developers on XDA were happy to just boot a new Android release on an older device. Thanks to Treble, we now have devices that can boot nearly fully functional builds based on the latest Android release within days of its launch. Once we have devices that support Generic Kernel Images (GKIs) in the future, perhaps we'll even have day 1 builds of new ARM64 Linux distributions running on our mobile devices instead of just Android.

If you're interested in flashing this Android 11 custom ROM onto the Redmi K20 Pro/Mi 9T Pro, you can find the download and instructions in the thread linked below.

AOSP 11.0 for the Redmi K20 Pro/Mi 9T Pro

Removed a link to the PE 11 build until further verification.