SOS is literally the only one I know haha.
I got really good at parsing Morse code for like a week many years ago, when my friend and I were playing Keep Talking And Nobody Explodes nonstop.
Discussion
Its honestly much easier than I thought it would be, of course there is reading it and there is hearing and interpreting it which is a different thing all together. I can probably read it off a paper party decently now but I don't know about audio lol
I think you'd get good at audio by actually talking to someone over a wire. Same as any other language.