Picnic landed in France, but the official integration dosn’t support FR as a country code.
I never made a home asisstant integration but it seems to boil down to this file : https://github.com/home-assistant/core/blob/624c3be3aed79f1d8321169abb5cb85098768160/homeassistant/components/picnic/const.py#L20
I tried opening up a github issue but was pointed here. If it’s not the correct place, feel free to point me to the correct place to ask about it !