Oh, and going back to the original post:
The idea I'd like to touch upon here is that the NPCs should address/interact with the player character based on their appearance - and, therefore, their perceivable sex - rather than their identity
We have Dror Ragzlin, a hobgoblin, who hardly hails from a standardly "civilized" society and is openly hostile towards the character, and yet he will also address them based not on what they look like but on their identity instead.
Otherwise why are some forms of oppression portrayed in the game - race-based, enforced - displayed openly and addressed, but misgendering somebody because they don't resemble the commonly percieved appearance of a gender they identify as is a sin that even roughhide mercenaries, slavers and brutish hobgoblin warlords won't commit?
I don't know how it happened, but we are now arguing about the exact opposite of what OP proposed, that being MORE misgendering and characters characterising you based on s*x, not gender. Now we are talking about removing all gendered language referring to the player character.
Why would, for example, Shadowheart, in a moment, say "they" instead of "he" or "she" referring to the PC without ever being prompted to do so, but never once address anyone else as "they"?
And all of a sudden it is not just a couple lines talking about the PC anymore, but all conversation, or immersion is broken because there is no consistency in the world.
