Well, I write in french a lot as well :) ("{" and "}" are only accesible with altgr), but if you remove 60% of the azerty layout, you'll need a lot of modifiers!

I checked the website a bit amd it seems the planck have "layers", and you navigate these layers with to keys: lower and raise. This sounds like an interesting concept. Pretty much like phone keyboards that have one page for letters, one for numbers and one for symbols.