Hello,
the App opens up many more possibilities for breeding various different genetics from people you meet online, and also exclusive items in the App which you can send to your Tama On device. You can still download the App although you're in France, I'm in the EU and I have been using it with no problems
If you're on Android, just download it from APK Pure:
https://apkpure.com/tamagotchi-on/com.bandai.tamagotchion
Just visit that link from your phone, grant APK Pure the necessary permissions to install on your phone, and download it from there
You will need to update the Tamagotchi ON App through APK Pure when it requires updates, not the official Play Store.
You might need to download APK Pure before downloading the above mentioned link/APK. Sorry, I forgot the exact steps how I did it, it's been around 2 months since I did. Here's the link to APK Pure in case:
https://apkpure.com/ I am definite that I didn't use anything else apart from these 2 links, so you should be able to pull it off
The installer/APK should go in your phone's downloads folder, which you can access through a File Manager app (my phone had one built in by default).
If you're on iPhone, just create a US account and you should find it in the list of apps. Hope this helps
As for recommendations, I have no experience with the new Tamagotchi ON Wondergarden, I have the Magic version and it's brilliant though
I highly recommend one of these new colour Tamas (Meets/ON), nothing to be hesitant about