Another chat app that may work is Wickr, which can’t be downloaded in China, but it can be brought into the country after being downloaded elsewhere.
The encrypted messaging service uses a VPN-like method to remain operational in nations where it might otherwise be censored. CEO Joel Wallenstrom told tech blog the Verge in 2018 that “people trust very secure stuff to Wickr, and they’re trusting us not only to secure the data but that we’ll get it where it needs to be.”