Almost all mini splits manufactured today are heat pumps by definition. They utilize a reversing valve, just like a ducted heat pump, to reverse the refrigeration cycle and produce warm air from the indoor coil instead of cool air.
There are many different styles of mini split heat pumps. Some are designed to produce heat even in extreme cold outdoor conditions, while others are best for milder climates. Some of these ‘low-ambient’ versions of mini split systems can produce sufficient heat indoors even when temps outdoors drop below -10 degrees!