Most companies these days use some bastardized version of scrum. Pretty much nobody does orthodox scrum. They either say they do and then do something kinda weird and homegrown or they say they use some variant of scrum (or another agile methodology) but do something slightly different. You’ll see SAFe (“scaled agile framework”, I ran into it in banking), scrum, you used to see a lot of XP but it’s not really in vogue anymore, lots of other things.

Read up on scrum, get some sense of it, and then don’t be too surprised when you start somewhere that claims that they do scrum and really they’re doing whatever whacky thing they could get people to go along with.

In terms of languages, those are all pretty standard. In bitcoin/lightning specifically, you will probably run into C/C++, python, and rust at some point. There are also some VERY passionate scala users doing some cool things. I wouldn’t stress about it too much. If you’ve learned a few languages, picking up new ones just becomes part of onboarding to a new project or company. For example, I’m working on a project with a LOT of Rust. We have a bunch of engineers that came from kotlin or golang backgrounds. So they’re learning rust right now. No big deal.

Yes, I think most companies do use some form of Scrum. I would say don't worry about Scrum. You'll learn it when you need it. But maybe others can share more experience.