Ergodox accent without international deadkey

I try to configure an ergodox-ez keyboard with developper layout but also to be able to type french text.
So I don’t want to set US-International layout because I don’t want dead key on all ' and ` when I develop.
Gnome Tweaks
All can be done by command line but I prefer using gnome tweaks GUI.
It can be installed with ubuntu software or with sudo apt install gnome-tweaks
Compose key
On keyboard & mouse part setup a compose key.

Enable the compose key and choose your preferred key.
In y case Right Ctrl

Erogdox config
With Oryx you can add modifiers on a key.
You can do it for most useful french accents like ` or '

Enjoy
Now you can type your new dead key and the required letter and enjoy typing accents.