Install Notify and Fitness for Mi Band from Google Play Store.
Enable the GPS and open Notify and Fitness.
Allow the localization access authorization and pair your Mi Band 4.
Pass all steps and pass "Notifications access" authorization.
Expand the menu with icon at left top, and go in "Settings".
Scroll down in "Basics" tab, and at "Mi Band firmware version" tap on "Update".
Accept the required authorization.
Tap on "Choose file" button and select the Firmware/Resources/Font file.
Tap on "Start update".
After update the Mi Band 4 will reboot (Firmware only).
Mi Fit will connect automatically at your Mi Band 4.
Uninstall Notify and Fitness for Mi Band.
Note- I will not be responsible for any bricked devices, the theme is tested by me and is ready to use.
Further versions will be released as they are released....
Credits to MagicalUnicorn for the theme above has York resources as base.
Credits to Dilute Water for the default watchfaces are changed with the ones of Google theme.