[meiraleal]

First you gotta decide what kind of software you want to develop. Or if you are doing it to get a job. The answers will vary a lot.

As a general recommendation easy to follow, I would recommend to learn JavaScript and only JavaScript. And you can go just for the most modern version of it without need to worry about things that make javascript complex: compiling, bundling, commonjs vs ES modules, etc.

JavaScript is a joyful language to work with and can get you very, very far in the software development landscape.

[solardev]

IMO full stack dev isn't just about any one (or several) languages but also all the in between stuff.

On the backend that could mean databases, scaling, containers, GraphQL, auth, scaling, etc.

On the frontend there's a lot of UX, styling, testing, responsiveness, races, waterfalls, async and lazy loads, parallelization, asset optimizations, etc.

In between, there's all the networking, CI/CD, permissions/IAM stuff, encryption, serverless, backups, Typescript...

The programming is actually some of the easiest stuff to learn, IMO, and not necessarily the most critical. You can't guarantee you'll end up working in a full stack JS environment. Often the backend is something else. I think Node backends are still relatively rare for older or bigger companies. But all the other adjacent skills are still just as (if not more) relevant.