I think being relaxed and using the obviously solution might be the best way for a start. Thanks for the hint!
You already found the bio.
But, if you want actual threads/posts, you can create your own community (using your username as the name, maybe?), and set it so only you can post to it. Then link to it in your bio.
Now you have a personal page you can make posts to.
Creating a new community and using that to post own thoughts / longer textes could be a nice way. Thank you a lot for this hint.