Undoubtedly, programmers are a major user of keyboards, and IDE developers love function keys for esoteric shortcuts for debugging, moving around, and running code. So why do so many split keyboards not actually have the function keys.
I think makers are missing out a huge audience.
I’m sure you have something that works for you already, but before I had a keyboard that just let me add the keys with firmware, I was getting by using AutoHotkey and a script that would turn double taps of an F-key into the F+12key.
I bought a little macro keyboard, but if I had the physical keys already, I’d be using them as macro keys!