Android one device have stock Android, doen't have justers and other navigation got 9gb Android fast but stock. Miui have more custom settings.
my old phone is A2 lite and I never back to Android one. you use miui if change you lose so much buy Mi9t(redmi k20) global version.
A3 is good phone but stock Android I doen't like,is you I use redmi note 7.