[Xiaomi Mi Mix 2S ROMs, Kernels, Recoveries, & Othe] Flatric:
First of all:

THIS IS NOT MY WORK, I'm only maintaining this Thread for [MENTION=5503041]Wooby[/MENTION] who gave me permission to do so. He compiled this Rom for our Polaris. All credit goes to him, thank you!

Features

General:

MD2 UI
Rounded UI
Pixel Lockscreen weather
Substratum Support
Compiled using SDCLANG
OTA Support
Signature Spoofing
Micro-G support
Lockscreen charging animation
In-built Oneplus Camera & Gallery(Oneplus Device only)

Status Bar:

Double tap to sleep
Statusbar brightness slide
Quick & Smart pulldown
Clock Settings
Breathing Notifications
Battery customization
Battery bar
Network traffic indicator
Carrier label customization
Notifications count
volte icon toggle
Bluetooth battery status
Old Mobile type style
4G/LTE icon switch
Data disable icon toggle

Quick Settings:

Layout customization
Brightness Slider customization
Auto Brightness icon
Bottom brightness slider
Running services icon toggle

Interface:

Expanded Desktop
Themes
Background Color(Light/Dark/Black)
Notification Color(Light/Dark/Black)
Accent Color Picker
Auto Night mode
QS Header Style
QS Tile Style
Font Manager
Rounded Corner adjuster
Dashboard toggles

Ambient Display:

Now Playing
Now Playing History
Always On Display
Ambient Display options(Tilt/Pick-up/Hand wave/Pocket)

Screen:

Smart Pixel
Screen Stabilization

Buttons:

Volume Rockers
Switch to make ringtone volume slider default
Dialog timeout
Volume steps
Keyboard cursor control
Reorient on rotate
Music Control
Volume Rocker Wake
Volume keys call answer
Power Button
Power Menu customization
Screen off power button torch
Hardware keys
Disable keys
Swap keys
Backlight timeout
Backlight adjuster
Accidental touch toggle
Single/Double/Long-press button action

Navigation bar:

Pixel animation
One-handed mode
Navbar Pulse
Navbar button Swap
Layout
Extra button

Gestures:

System Gestures
Jump to camera
Prevent ringtone
Swipe up on home button
Full gesture mode
Swipe to Screenshot
Swipe Gestures
Navigation
Swipe up gesture
Edge gesture
App Circle bar
Pie control
Gesture Anywhere

Lockscreen:

Double tap to sleep
Media cover art
Lockscreen Visualizer
Clock/Date Font stlye & Size
Weather unit
Unlocking
Pin Ripple
FP authentication vibrate
Face auto unlock
FP unlock on reboot
Pocket detect
Quick Unlock
Scramble layout
Direct unlock
Disable Lockscreen Elements
Disable Quick Settings
Disable Statusbar
Lockscreen charging info
Hide lockscreen bottom elements
Lockscreen shortcuts

Recents:

Recents style(Pie/Oreo/OmniSwitch)
Oreo Recent customization
Clear all button
Memory bar
Immersive recents
Hide app from recents

Notifications:

Lights Customization
Charging light
notification light
Blink Flashlight on Call
FC notification disable
Disable Immersive messages
Heads Up
Customization
Less Boring Heads Up
Ticker Notification
Ticker Animation
Misc
Toast Icon togggle
Noisy Notification toggle
Force Expanded notification
In-call Vibration customization

Animations:

Disable animation
Animation Duration
Animation customization
List view animation
QS tile animation
Power menu animation
Screen off animation
Toast animation
Scrolling Cache

System:

Signature Spoofing
CPU info
Privacy Guard
Chooser Activity blacklist
Burn-in protection

IME Settings:

Selector notification
Auto keyboard rotation
Disable fullscreen keyboard
Show enter key

Battery Saving:

Sensor block per-package
Alarm Blocker
Wakelock Blocker
Suspended Actions
Doze settings

Miscellaneous:

MediaScanner behaviour on boot
Wake up on charge
Launch music app
Screenshot type(Fullscreen/Partial)

Other Features:

Advanced Battery info
Night Light brightness options
On-the-go mode
Prevent Accidental wake-up
Seperate ringtone for SIM1&2

QS Tile Shortcuts:

Heads Up tile
Caffeine tile
Ring mode tile
CPU info tile
Suspended action tile
Smart pixel tile
Now playing tile
Ambient display tile
AOD tile
Screenrecord tile
Stabilization tile
Gaming Mode tile
Screenshot tile
Accidental touch tile
Alarm/Calc/Phone/Camera/Music tiles
Expanded Desktop tile
Havoc settings tile
HW key tile
LTE tile
Navbar tile
On the go tile
Pie control tile
Reboot tile
Sleep screen tile
Accent picker tile
Volume panel tile
High Brightness tile

Device:

Spectrum Power Profile
Screen Calibration
Custom Calibration
High Brightness Mode
Off screen gestures
D2TW
Slider customization
Vibration strength slider[/HIDE]

Installation

Always have a Backup of your files, you never know if you'll need it!

First time:

Latest Firmware+Vendor needed

Make FULL WIPE (system, data, dalvik, cache, format data -> yes)

Flash ROM

Flash Gapps and Magisk

Reboot device

Update:

Wipe cache/dalvik

Flash ROM

Flash Gapps and Magisk

Reboot

Links

ROM: Click​

Recommended Gapps: Open Gapps Nano -> ARM64, 9.0​

Mi Mix 2s Telegram group: Feel free to join if you need help or want to stay up to date​

Credits

[MENTION=455439]bgcngm[/MENTION]

[MENTION=8203960]palaych[/MENTION]

Sources

https://github.com/Havoc-OS

https://github.com/LineageOS/android_kernel_xiaomi_sdm845/commits/lineage-16.0

https://github.com/LineageOS/android_device_xiaomi_polaris/commits/lineage-16.0