Portable Air Conditioners are usually equipped with a heater so you will be buying both if you purchase one. Most units will cools areas up to 600 sq. ft. and the heat pumps can function in around the same area (usually a little less) when it gets cold.
Portable AC’s bring comfort to whatever room you want, especially garages, or sheds. Don’t buy one unless it comes with programmable electronic controls and auto-restart. That way you don’t have to constantly keep turning it on, and you can maintain a consistent temperature.