Where I work now, almost 100% of our clients are female and were assigned female at birth. The guys who come in either are buying gift cards for their wives or else make a beeline for the "man cave" (the place at the front of the store where you can sit on the "ledge" in front of the window display and play on your phone while your wife tries on clothes). Most of our clients are also older and vastly wealthier than me, and many demand...um...expect a certain amount of respect, so the word "ma'am" or "ladies" comes out of my mouth often. I've been wondering how to show that same respect to a non-binary person should they come to our store.
Sadly, you can't really mash up "sir" and "ma'am" to make a good new, non-gendered term of respect. "Mir"? "Sam"? A bit off topic but...not too long ago, I ran across a new (to me) word to describe the offspring of your sibling who identifies as neither male or female: nibling. I love it; we have "sibling" to refer to either a sister or brother, so why not "nibling" to refer to either a niece or nephew? It's also so much easier for me now to type "niblings" rather than "nieces and nephews" <g>.