You use Wechat
in China they use Weixin
The two apps are interprobable but not the same
Honestly can’t tell; I have a US based account, and when I was in Taiwan for CNY for a month, it still showed me mostly US content (even on the For You page) and if I remember correctly, either nothing local at all or very small amount, despite the fact that it’d adjust for Idaho (my home) and whichever US state I was in (e.g. I’m working in Minnesota and see a lot more Midwestern stuff on FYP).
Maybe you’d have to register for an account in Taiwan if you’re planning on doing something like this instead of using the account you registered in Denmark (if applicable).