Most notably PGP has been available in France for decade and has never received any form of approval as far as I know.
Just read developer FAQ for the store you want, there is a requirement of "Declaration approval from French ANSSI authorities." which links to http://www.ssi.gouv.fr/en/regulation/cryptology/
"...
However supplying, importing and exporting cryptology means in and from France are regulated activities. These operations are either subject to a declaration or an authorisation process.
ANSSI records declarations and investigates requests for the authorization of cryptology equipment and services in accordance with French and European Community legislation."
So you have to send them ANSSI declaration and get an approval to submit an app to the store.
If you are distributing something through the website which is available everywhere then you can ignore that since there is no entity which would control that you follow French law, but it just a technical details. The law is the same for everyone I believe.
Regarding Telegram, Signal, WhatsApp, etc.: I believe they have sent all the documents and got the permission/registration in all regions they are available in and which require that.
Big app stores like AppStore or Google Play Market make you comply with the law every time you submit an app with cryptography inside.
"...
However supplying, importing and exporting cryptology means in and from France are regulated activities. These operations are either subject to a declaration or an authorisation process.
ANSSI records declarations and investigates requests for the authorisation of cryptology equipment and services in accordance with French and European Community legislation. "