If you ask the WeChat app, it will give you a QR code with which other users can connect to you. Mine is above. It scans to https://u.wechat.com/IJMbz_RPd_5wuWdlgSd61-w, but clicking that doesn’t seem to do much, at least on a computer. Apparently, there used to be a format for WeChat URIs, under which the link would be weixin://dl/chat?IsaacSheff, but I hear that’s discontinued.
Anyway, my username is “IsaacSheff” on WeChat, although I check it very rarely.