A rather random post while I think of it. If you love French cosmetics and toiletries, you are supposed to visit a store near St. Germain called City Pharma. I went in there looking for COVID testing so I don't have shopping experience, but I did some Google and it's apparently quite well known and highly recommended. As most have noted, it's pretty crowded and frantic, it's not just a pharmacy it's like a small department store. You're not there for the pleasant shopping experience but rather to fill your basket with as much stuff as you can carry. Note that it has several stories so expect to spend some time there.
Also if you didn't know, some drugs which require prescriptions in the US are available OTC or from a pharmacist in France without one. Do some research beforehand if this could apply to you.
Here is one blog I found extolling the virtues of City Pharma: