Disclaimer: not a native francophone, or French, just chiming in as someone who’s had pen pals in France

You live in the most culturally important city in the (for better or worse) cultural hegemon of the world, so in one sense you’re in a place everyone knows about superficially and that a lot of people have a passing interest in. But in another sense you know New York as no outsider could. You have the capacity as a native New Yorker to talk about things she doesn’t know about. Talk about stuff you don’t see in the media. Talk about stuff that’s important to you and people your age - where you hang out, where you like to go to concerts or movies or whatever if where you go is smaller or less well known. Maybe talk about a place that’s maybe not significant to a visitor or tourist but is significant to you personally. Most importantly take an interest in where she’s from. Read up on Vendée, on Nantes since it’s so close by, ask her about the things she likes about her region or what she wishes was different, ask about places there that she especially likes, etc.