An important French singer who hasn't performed at the major US opera houses is Véronique Gens. She began her professional career right out of school with William Christie and Les Arts Florissants. She is a lyric soprano who specializes in the French Baroque.
We know she performs outside France at least occasionally because I saw her at Wigmore Hall during the time I was living in London. I was annoyed that she hardly looked up from her music stand throughout the recital, as though we were simply not there.
I own a few of her CDs, including the ones shown below. She's rather low key, but still very much a pleasure to listen to.
The examples are neither one French Baroque. I wanted something with visuals.
This is from one of her recordings. I always feel it is important to hear French singers singing in French.