I really like split space for TKL, it's extremely useful for spaceFN type layouts. I've been converted to spaceFN after using my alice for a while, and it's actively one of my favorite things now
SpaceFN means tapping space is Space, holding is Function, or? Why does that require split?
doesn't require split, but i can use the small key as another layer, so i have access to three layers with just my left hand, allowing for extremely fast navigation and inputs in excel
the way i personally do it, i have it as tap for space hold for FN1, then the small key is hold/tap for FN2
so, i use my left hand to type in numbers, and my most used commands (=INDEX(MATCH, mostly) are on macros in one of the FN layers)