Not a France sim, but tmobile UK has a OK data rate in all of EU. I think it's about 1.5 pound/MB or so. Thought I'd menton in case you can't find anything cheaper.
http://www.t-mobile.co.uk/services/g...ountry/france/
Edit: Added link and changed UK to EU.
Phones: Xiaomi Mi Mix 2, Samsung Galaxy A50, ASUS zenfone 3,
Sim cards: AT&T (Contract), 3 UK, Piranha Mobile