Lots of pilots would like autopilots in single-engine aircraft, and lots of operators would also, and would install them immediately if they were available. Unfortunately, none are currently available,
AFAIK. Light, reliable, and relatively inexpensive models are essential, and there's the rub. Any piece of equipment that costs as much as the airframe may as well not even exist, but I'm not aware of any available at any price. Work is in progress, but it's far from ready to install.