Generally most good quality siphon feed air spray guns can be pressure fed but pressure feed spray guns are not really suitable for using with suction feed paint cups
As an alternative to using a pressure pot in conjunction with spray painting, many manufacturers offer a range of double diaphragm pumps that basically perform the same task.
Although a double diaphragm pump has many more moving parts and is much more complex than a simple pressure pot there are several benefits which may make the additional cost of a double diaphragm pump viable in certain spray painting environments.