Jinja is a template rendering engine and you will encounter some sort of template rendering engine in each language. Jinja is a pretty standard tool and almost every language has some sort of Jinja equivalent. Ruby has Liquid, Node has Nunjucks, Java has Jinjava, Go's default templating engine is easy to pick up if you know Jinja, Helm charts are easier to pick if know Jinja . So learning Jinja is a good thing.

If you are currently not working my first suggestion is to study both the frameworks and get a good grasp of those. If you didn't get confident with Django in the first place you should reconsider going back and study more. Get a video course with some code-along and produce some simple application you can showcase on your interviews. If you already took a course take a different one. Another trainer could be more effective and you could experience something new with different excercises. There are lots of both free and paid courses out there. When you will get confident with Django get your feet wet with Node.js because it surely worth it. Node is very different from Django from some perspective, it looks more like an asynchronous version of Flask to me. Be sure to have a good knowledge of ES6 first, because it will be really useful to understand the Node best practices. Study as much as you can now if you are not working. It will supercharge you for the future...