Meh, we imported the module so we don't have to go through another upstream to make changes to the script, but then ended up not using the fork at all. https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1136
https://gitlab.gnome.org/GNOME/gnome-shell/issues/997
The README describes the steps in detail, but most of it is abstracted away by the update-osk-layouts.sh script.