I have created a few TWRP installable Zip files to modify a Mi Max 2 (or indeed any other MIUI8 phone) in order to make the Max 2 more closely resemble a Stock Nexus or Pixel phone.
There are three sets of zip files, all of which patch Xiaomi.eu firmware:
MIUI to Google Apps - this zip replaces the MIUI apps with stock Android apps. This includes the Launcher, which is replaced by the Google Now launcher by default
Google Now and Pixel Launcher - These install either the Google Now launcher (included with the MIUI to Google apps, but allows us to swap between Pixel and Google Now), or the Pixel Launcher, which also modifies the build.prop to enable Google Assistant. Note that these are generic zips which can be used to install either launcher as a System app on any device.
MIUI DPI changer for 325dpi or 440dpi - This will work with any MIUI device with a 1080p display to change the DPI from 'high resolution' (325) to 'low resolution' (stock 440).
Firstly you will need to unlock the bootloader of you Xiaomi device, flash TWRP and copy a Xiaomi.eu ROM into the file system of the device.
1. Install the Xiaomi.eu ROM
2. Install the MIUI to Google Apps package
3. If you would prefer to use the Pixel launcher with Google Assistant then flash the Pixel Launcher package
4. If you would prefer to fit more content onto your screen (e.g. for a Mi Max / Mix series device) then flash the 325dpi package.
I have written up exactly what is removed and installed in the MIUI to Google Apps package here in case you wish to see precisely what changes are being made to the OS.