I use the hyphen key, and hit it once for a hyphen or for a minus sign, and I use it twice for an em dash.
At some point, many things I type into started replacing "--" with an em dash, but my precambrian computer typing muscle memory is fine with "hyphenhyphen" meaning "em dash".
I will admit right here in front of god & everybody that I'm pretty sure I've never typed an en dash at all.