Being self-taught, I never formally learned algorithms or data structures. I got my job at AWS and have never used LeetCode. I got a copy of Cracking the Coding Interview and made sure I could solve all of the problems without first reading the solution. If I could, I went on to the next one. If I couldn't, I read the solution and then implemented it on my own to prove to myself that I understood it and could do it.

That's all. One book. I ended up writing maybe 3 or 4 small functions, e.g. quicksort in JavaScript. They didn't end up being very important either in the interview or at my job, but I'm glad I challenged myself.

The majority of my time was spent studying behavioral interviewing, not technical aspects. System design and behavioral knowledge was significantly more important than the technical bar, which I met easily.

You can use your language of choice when interviewing. If you are strong in your language, I don't think you have much to worry about.