You already mentioned the points for your growth in your question itself. Others can suggest topics or areas which you may find interesting. Have you done any research on those topics that others suggested? Is there any particular topic/area that you find interesting and you feel like you want to learn more about it?
Regardless of the topic/interests, the only skill I have seen very valuable and pays really well regardless of who you are is the skill of "knowing where to hit the nail with zero to minimal impact". This is the only survival factor of most people who are selling their seniority to their employer. Some knowledge/skills is like wine. Even if it ages, it is still the same today and matters most. Some knowledge/skills is ephemeral. It will go away to be replaced with much more efficient knowledge/skills in some time. Try to gain eternal knowledge and skills like "where to hit the nail" instead of focusing on what hammer to use and what the nail is made of.