Great job refuting your own point. QQ is owned by the same parent company as WeChat (Tencent). Tencent is also implementing the Chinese Social Credit Score system, and so in my humble opinion, is the tech arm of the chinese government.
It really comes down to what "basically the only one" means. But I wouldn't aggree that "google hangouts is basically the only messaging app" would even extend to all the other messaging apps google ever produced. (Please note that this is an example of formulation and what I consider that encompasses, not that hangouts is the only messaging app in any context.)
But besides that: There exist further chinese messengers and non chinese messengers that are not blocked in china.
The rest is, in my opinion, irrelevant to the topic of wechat being the only chinese messaging app.
