Finally found one: https://meaningcrafters.com/produit/powerbank-alex/
I don't speak French but placing the order was quite straightforward. Shipping costs were a bit high, but totally worth it. ~~Highly recommended!~~
Edit: Probably too good to be true, see discussion below...
Almost certainly, everything was made in China, shipped to France, and assembled in France.
Source: I work in open hardware. Almost everything comes from Shenzhen