The good news is that the MIUI 10 Global Beta ROM 8.10.11 brings latest Android 9 Pie to Xiaomi Mi MIX 2S and Mi 8. The OTA update is seeding to all supported devices now. Go to ‘Updater’ app and check for the new update manually. You can also install the MIUI 10 Global Beta ROM 8.10.11 manually by downloading recovery or fastboot ROM.
MIUI 10 Global Beta ROM 8.10.11 Full Changelog: If you own a Redmi or Mi phone that is running on Global Beta ROM, download the Recovery ROM from here and flash via Updater app. If you have installed TWRP custom recovery on your device, then you can install the recovery ROM via TWRP. If you are using MIUI 7 / MIUI 8/ MIUI 9 Global Stable ROM, then to upgrade to MIUI 10, download the Fastboot ROM [here] and follow the fastboot method. For newbie, follow this detailed installation guide for flashing MIUI ROM on Redmi or Mi phone. This guide explains three methods for install stock firmware on a Xiaomi phone.
