Something for semi-private (group or 1:1) chats (rather than public posts), with English-language support, perhaps like Telegram, WhatsApp, etc. Ideally run by a Chinese company (not a US company doing business there or one with US partners like TikTok) with servers, domain etc. in China. I was looking at QQ a while ago but I think their international app version was no longer offered. Wechat is currently closed to registration. Thanks!
Unfortunately WeChat is probably your best bet despite closed registrations. If you can find someone with an account they can register you by scanning their QR code, which is the only way you can register as a foreigner without a Chinese ID card I think. Once you have an account you can register anyone else you want to talk to through the same method. WeChat is mostly a domestic chat service and the international version is mostly used by the diaspora to talk with friends and family back home, so they don't really expect or necessarily want people outside this demographic to use WeChat. If security or privacy is what you're looking for, sorry, but even if you use some esoteric open source p2p encrypted chat service with a userbase of 3, google/apple can still know everything.