Industry skills/frameworks to learn for META engineer

Hi I’ve been at meta since I graduated. Promoted to 5 and I do well in the company but basically only know hacklang and some react. I have no clue about the standard tools in the industry or even GitHub. We use mercurial. So - I want to do a project where I can increase my employability and be able to do system design interviews. What would you recommend? 1) build a hobby app in react native, deploy it. Learn to use docker/aws and node.js 2) ?? 3)?? Would appreciate suggestions from experienced industry engineers. Thanks