You can use GitHub since it’s one of the few platforms (if not the only) that won’t be blocked in China and Microsoft is very unlikely to censor your repository.

WeChat and other social media will of course shadowban messages containing a link to your repo (assuming it become popular enough to be noticed) but you can find creative ways to bypass the blacklisting (e.g. share link in a picture, with spaces in the link, forking the repo and sharing the forked one, etc.)