Hacom have a modified image that they distribute for their own hardware but anyone can use it. It has several differences to the main pfSense image, primarily it uses keyboard/vga for it's main console output. The pfSense nanoBSD images use the serial port for the main console.
Use the pfSense images unless you can't use the serial console for some reason.
When you've installed the image the package manager will only display packages that can be installed.
Steve