Missing keyboard layouts linux in settings

Solution 1:

The last time I checked, there sadly is no way to do this locally in an easy way. Iirc you need to add your layout /usr/share/X11/xkb/rules/base.extras.xml. However this will be overwritten on every update.

See this commit for an example: https://gitlab.freedesktop.org/xkeyboard-config/xkeyboard-config/-/commit/3deb5d2214e2fe7fbf1c4bb259c1c5fd90619290

Then you need to refresh the cache, on Debian-based distros you do it with sudo dpkg-reconfigure xkb-data, else try sudo rm /var/lib/xkb/*.xkm.

Since it seems you only want to use a subset, I recommend you to just use it and ignore the other keys.