Got my Redmi Note 9 Pro around start of 2021, since receiving MIUI 12.0.3 i never updated from there, there are no packages whatsoever to download, tried talking to the assistence and...
Download and Install Lineage OS 19.1 for Redmi Note 9 Pro (Android 12)
Lineage OS 17.1 on Redmi Note 9 Pro | The Best ROM for Redmi Note 9 Pro? - YouTube
GitHub - Redmi-SM6250/android_device_redmi_excalibur: AOSP device tree for the Redmi Note 9 Pro Max
Great battery life on Redmi note 9 pro with costum rom much better than stock,even tho the phone is 2 years old.What is your experience with costum roms in terms of battery