I have a Xiaomi Mi Mix Fold, running MIUI 12 / Android 11. The settings say that the running kernel version is 5.4.86-qgki-g629683a5515c.
I know that the purpose of the Android GKI is that the kernel can be updated without having to update the rest of the device. Does this mean I can download a newer Android GKI from Google, and install it?