I was deceived.
Prior to buying my iPhone 8 I read that Apple’s 3.5mm to lightning adapter didn’t support audio in for earphones with a microphone. Not so! It works quite well with Apple’s EarPods.
It probably doesn’t work with other earphone microphones though. Apple’s EarPods have a different arrangement for the audio-in connection from some other earphones. I looked into this years ago and it wasn’t clear to me how much of a standard there really was. I dimly recall that Apple, shockingly, was different from most.