Many of the things you're talking about build on top of JavaScript/ES6/Vanilla JS. So you should definitely push on to a solid grounding in the base language first.
If you are not comfortable with JavaScript, adding React or Electron is just adding a layer of complexity before you're ready.
I'd also say - with a 2-3 year window, there's no real harm learning both JavaScript and Python. By learning two quite different languages you'll see where you are learning _programming concepts, _which helps avoid getting too preoccupied with syntax/language.