I use the same grind I use for drip. espresso grind, in my experience, over extracts.

a little bit more coarse than an espresso grind. remember that a moka pot doesn’t make “real” espresso but still creates a strong cup of concentrated coffee. you don’t want a super super fine espresso grind but still want something finer than say what you would use for a french press or a v60

I've had my best results somewhere between espresso and drip! Also, I've enjoyed medium or dark roasts better with the moka since the light roasts will tend to bring out too much acidity because of the finer grind.

Espresso I'm pretty sure

Medium-Fine

These bad boys are very versatile, you can use pretty much any grind. It's gonna be pretty concentrated if you use something like a espresso grind, and sort of weak if you use a french press grind, it goes from personal preference. I just tend to use a pour over grind.