I have download and flashed its lates updated version xiaomi.eu_multi_kuntao_8.9.20_v10-7.0.zip and it also has face unlock . And I have found the way to enable screen button and full screen gesture . I have also enabled portrait mode in stock camera of updated version .
""**To enable screen button follow these steps
Install any file manager app that supports root access such as Solid Explorer, MiXplorer
Open the app and grant root permissions. Go to the root folder > system > build.prop
Open it with the text editor and scroll to the bottom. Leave a line and enter the following text on the next line.
Code:
qemu.hw.mainkeys=0
Save the file and reboot your phone**""
Link for latest version
Miui portrait mode camera in attachment ...flash it
