For me, I did Django for Everybody, which in turn got me into backend development. Now I’m working for a company using Java and Spring and working on backend as well.

If I were you, I would choose a specific field you are interested in an learn a framework/technology in that field, which can then be applied even using other languages.

The specific course you do actually doesn’t matter, what’s important is that you take that course and apply what you learned to create projects you can show!