How to add number row in google keyboard with the "azerty" layout?

[AC Question]

I'd like to add the row number on the top of the keyboard. I know that it's possible by changing with the "custom input style" choosing "Pc" layout, but this option seems to only allow to have a qwerty keyboard.
Do you have any other solution using the native google keyboard? (I am not interested in Swiftkey).

Thank you.