Would need to build something more designed for that purpose. Definitely not going to allow people to inject their own HTML into the site (there’s all sorts of issue ranging from the site not rendering properly for them because they added incorrect HTML to it being a security issue if a user adds malicious code).
If it’s just intended as a notes thing for the user and not others, maybe starting a private conversation with themselves would be the best option? You wouldn’t be limited to 1 link per type and would have a lot more flexibility (like images and more formatting options)?