I use a split keyboard which not only doesn’t have a row of F-keys, it doesn’t even have a number row; it’s three by six keys on each half.

I use chorded keystrokes for F-keys. I have a layer key (named “Lower”, and located where the ‘Windows’ key is on normal keyboards); hold that down with your left thumb and the middle row of keys on the left split (caps lock -> g, under a qwerty layout) become F1->F6. And the bottom row of keys on the left split (left shift->v) become F7->F12.

I actually find it a whole heap easier to hit those key combinations than trying to find various physical F-keys three rows away from the home row; I think I’d actually set up a macro like this even if I was using a full-sized keyboard; I just find it to be easier.

(although I don’t actually use F7->F12 for anything, normally; that might be a little awkward in terms of finger positioning and I’d think about maybe moving them over to the right side of the split if I used them with any regularity)