Xiaomi might have not pushing android 7 to Mi Pad after all but developers are still pumping out new and latest firmwares for it. The best one is the crDroid android 7 ROM which is based on lineage OS which is further based on the android nougat. It has pixel look and feel to it. Everything is said to be working on it except camera which no one uses on their tablet anyway.
Make sure to download gapps and flash them in recovery since it does not come with any.
Download the ROM from here and flash it using mi pad twrp. Feature list of Mi Pad Android 7 ROM:
Pixel look and feel, OMS-rootless (theme engine) Supported. Install Substratum from Play Store, Google Assistant, LineageOS 14.1 – all mods and features, Viper4Android Equalizer, Dolby Sound, StatusBar: Network Traffic, StatusBar: SU icon toggle, StatusBar: Ticker, StatusBar: Hide/Show icons, StatusBar: Hide/Show data activity arrows, StatusBar: BatteryBar customizations, StatusBar: Date customizations, StatusBar: Battery styles, StatusBar: Tap to Sleep, StatusBar: Clock styles, StatusBar: Custom logo customizations, QuickSettings: QS Header image customizations, QuickSettings: Weather tile integration and customizations, QuickSettings: Tiles customization, QuickSettings: Brightness slider toggle, QuickSettings: Optional brightness icon, QuickSettings: Vibrate on Touch, QuickSettings: WiFi easy toggle, QuickSettings: Bluetooth easy toggle, QuickSettings: Data easy toggle, QuickSettings: Location easy toggle, Navigation: Toggle navbar, Navigation: PIE navigation, Navigation: DUI – SmartBar / Fling Toggle, animations and customizations (+ One Hand mode), Navigation: Dynamic Nav Bar Color, Navigation: Pulse – smart visualization, Notifications: Power notification controls, Notifications: Force expanded notifications, Notifications: Toggle immersive mode messages, Notifications: Breathing notifications, Notifications: Headsup Snooze, Notifications: Headsup Timeout customization, Display: Ambient Display customizations, Display: Transparency Customizations, Display: Blur Personalizations, Display: Expanded Desktop Customizations, Display: Scroll Animation Customizations, LockScreen: Screen shortcuts, LockScreen: Toggle longpress for screen shortcuts, LockScreen: Swipe shortcuts, LockScreen: Toggle media cover art, LockScreen: Toggle clock, LockScreen: Toggle date, LockScreen: Toggle alarm, LockScreen: Toggle status bar, LockScreen: Tap to sleep, LockScreen: Toggle longpress torch, LockScreen: Cutomize number of notifications, LockScreen: Toggle power menu for secure lockscreen, LockScreen: Toggle quick settings access and hide swipe shortcuts for secure lockscreen, Powermenu: On-the-go mode – camera overlay, Recents: Immersive Recents, Recents: Hidden apps, Recents: Toggle OmniSwitch as default Recent view, Recents: Toggle Slim Recents as default Recent view, Sound: Charging Sounds customization, Sound: Toggle screenshot sound, Sound: Live customization for number of volume steps, Sound: Less frequent notification sounds, Sound: DND customizations, Animations Customization for Toast, System, etc, Miscellaneous: Clock Widget, Miscellaneous: Wakelock Blocker (experimental), Miscellaneous: Partial / Full screenshot selection option, Miscellaneous: Toggle suggestions on Settings dashboard, Miscellaneous: Toggle summaries in Settings, Miscellaneous: Toggle auto-start music player on headset detection, Miscellaneous: Show CPU info overlay, Miscellaneous: Disable Force Close notifications, Settings/Sound: Increasing Ringtone, 15 New Quick Settings Tiles including Caffeine mode, Expanded Desktop and Sync, Settings/Security: Quick PIN/Password Unlock, Default sounds from latest Nexus image, Stability and performance improvements, ART Optimizations