I didnt see anyone answer your question yet, so I figured I would answer.

I was able to see your posts and comments, and Im from another instance. (saw your post on a different instance and then found this comment)

Posting seems to depend on the instance’s rules. Others can you see where you been so I would always assume its public. Good news is that its easy to make multiple accounts (to separate activity), some dont even require an email depending on the instance.

Hope this helps.