[GreG L.]

Not according to ever article and every manufacture with data on the internet.
The optimal temperature range is for conventional mini split heat pump operation is over 25-30 degrees Fahrenheit. As the temperature goes down to 40 degrees, the heat pump starts to lose efficiency and is no longer the most efficient heating method once the temperatures go down to 25 to 30 degrees. Oct 21, 2022

Mid-level mini splits run at 100 percent efficiency down to 20°F and typically require a base pan heater. These work well for heating moderate to cold climates. Economy-level mini splits run at 100 percent efficiency down to 30°F and may shut off at temperatures below 20°F. These are best for moderate to warm climates.

A typical high end ($$$) Low Ambient Temp Mini Split.
These Pioneer mini split heat pumps are built to withstand even the most freezing temperatures, all the way down to -13°F outside. Their auxiliary crankcase drain pan heater in the outdoor condenser unit allows for reliable heating in frigid outdoor conditions.