I bought my mi5s from banggood. It has global stable 8.2.1 and I believe device is unlocked (in developer options it states that miui is unlocked). Does it mean that I only need to flash twrp and rom and I'm done? Later I can update by updater app?
To see if it is unlocked just install adb drivers in Windows, connect the phone in fastboot mode and in the adb window digit :
fastboot oem device-info
Strange that it is already unlocked, mine was too.