I had a problem with an extremely steep slope about 300 yards long (a proper mountain road) that was also a bad surface (gravelly). I drove up it steadily at low speed, but got nothing but wheel spin no matter how gentle I was. With the guidance of someone who'd driven up that road lots, we tried a few different things.The e-Kona accelerates like a bat out of hell - be gentle with the pedal at all times is the only real thing to beware of, and yes the driving mode button on the centre console allows you to scroll through the three modes to eco mode - the mode you have chosen is briefly displayed on the screen to the right of the speedometer for conformation of which mode your press of this button has just changed into. Do not press this button whilst driving until you have driven the car for a while. Some people always drive in eco mode.
Regen is like quite like engine braking, just better, and with three levels it is something to play with over time.
As for hill climbing near your garage, accelerate slowly, don't back up or anything, EVs have instant tourque so backing up won't help. You will notice that the e-Kona climbs hills as effortlessly (and as silently) as it drives on the flat, if you accelerate too hard you will spin the wheels and potentially slide out of control. That solid low slung battery makes the whole car heavier which helps the grip level too.
I ended up taking a run up, and essentially rallyed my way up at speed, using momentum and the natural bumpiness, and curves in the road giving me occassional better grip which I took advantage of whenever I felt the suspension dip.
Bizarrely, I had also gone into sports mode and turned off traction control. None of that made any sense to me whatsoever - but it all seemed to work. It might have been that Sports mode simply helped me get better speed up quicker, and that the lack of traction control made me just be more tuned in to how I used the accelerator.
Also - with hindsight, I made the mistake of asking everyone to get out (four people) - thinking just as if i was in an old car, that it was struggling with the weight, which was obviously wrong as there is no shortage of torque, and actually the extra weight would have helped with grip.
Better tyres, and more weight would both have helped much more than my rallying driving style!
Also, as Ian said,Re-Gen can be increased or decreased as you drive - in snow on a downward slope, you might well need to lower it using the paddles (right to lower, left to increase) as the maximum level is pretty much the same stopping power as soft braking, which in extreme no-grip conditions on a downwards slope might be too much and could possibly lock the wheels ( assuming there is no ABS equivalent for re-gen... which there might be!)