In Xinjiang, the Uighur population are obliged to run a version of Android with surveillance software installed on it that is constantly phoning home about all activity on the device. So, even if it were possible to install a chat app that evades the Great Firewall, everything that one reads and types on that phone would still be sent on to the authorities regardless. Belarus is a dictatorship, but far less authoritarian in the digital realm than Xinjiang.