I'm not the parent commenter, but I use a Dygma Raise (60% split kb). It has some issues but navigation hasn't been a problem. I use two of the thumb buttons as momentary (push-and-hold) layer shifts, with hjkl (and asdf) becoming arrow keys as long as that navigation layer is active, and qerf/yuio becoming home/end/pgup/pgdown in that navigation layer.