Feature Request: Implement "Fn Tg" key functionality

I noticed that the Librem 14 keyboard's right Shift key has a "Fn Tg" alternate function, but as I messed around with it, nothing seemed to happen. I then found this forum thread, in which MrChromebox said the Fn Tg key wasn't mapped. I mentioned the forum thread in the #community/general room on Matrix on August 26 2024, and Jonathon Hall added that the functionality would require a function in kbscan.c, and then the new function would need to be assigned in the key map.