Echo (they/them)

You are correct in that “Mx” is most often pronounced as “mix”. It isn’t a direct abbreviation like “Mr” is to “Mister”, but rather derived as a neutral variant to those types of honorifics, so don’t over think it. This is the wild world of the English language after all

Yes chef!

Oftentimes I just leave out honorifics when I am unsure of the gender or preferred terms of the person I am speaking with. If I know for a fact that they are non-binary then “Mx” can work, though not everyone is fond of it and I would hate to offend. Honestly I usually just substitute it in ways such as the below (though i speak pretty casually in general).

What can I do for you friend?

Sure thing love

Have a nice day hun