I recently got a Royal Kludge RK84 mechanical keyboard. However, I could only find the US layout variant. As I need to often write in French, I had to tweak it to correctly type some diacritics. I could have used the US international layout but like written in this article, dead keys are a pain to deal with and accents are reversed.
To fix that, I used the file provided by the author at the end of the article and created a patch file for /usr/share/X11/xkb/symbols/us. To apply it, download the patch and run patch /usr/share/X11/xkb/symbols/us < us-altgr-intl-fr.patch in your terminal.
It will change the existing “English (intl., with AltGr dead keys)” layout. Then, configure your desktop environment to use that keyboard layout (which was quite easy on GNOME). And, it’s done! Now, you just need to use AltGr to type most of the French diacritics. Typing French quotes and accented caps is even easier with that layout compared to the default French one or its new variant. You don’t have to rely on some weird Alt + number combinations anymore!
Also, the latest version of the us file can be found on the xkeyboard-config gitlab repository. You should check it out from time to time to update yours.
See you again, have a nice day!