If anyone assumes me to be they when I've spent nearly 50 years on this earth being a she, I'd be pissed off.
But some people think we shouldn't assume gender, so i don't think it's beyond anyone's comprehension to understand that automatically not assigning an appearance-based gender to someone when you meet them is just polite. And if someone refers to you in the third person as "they" when you're not there, there is no harm. And if they do it when you are there then all you need to say is "oh, 'she' is fine" or whatever and everyone continues on their merry way.
It doesn't need to be a big fight with people getting their backs up.
Having said that. I have always worked in male dominated industries where if anyone has had even the slightest inkling when dealing with me by mail that i am a woman, my expertise and experience is questioned. It is a disadvantage to me to add "she/her" to my email sig when my email address and sign off are clearly designed (by me) to be non-revealing. (initial, surname). And this is why i won't put it in my signature.
When email etc first really took off in the world of work, we often got emails from our eastern European based staff with a "firstname, lastname (mrs)" type of sign off. It was, because i asked, because they didn't like getting emails addressed to "dear Mr x" when they were "Mrs X". It seemed important to them so i took note. But out of politeness not some weirdly pre-woke way.
I can't really get excited about it all, as long as i'm not being abused for my stance.