Based in the pockets (Slanting up with two buttons), it looks like he’s wearing a US M42 paratrooper jacket:
He’s wearing a German Heer cap. If he served with the US, odds are that he simply found or acquired it somewhere, and he’s modeling it here as a goof.
Who knows how he came across it. He could have stumbled upon previously occupied German positions, took it from a prisoner, or traded with another GI. Really impossible to know for sure.
Hello there! As your question is related to looking for identification/information regarding military personnel, our Guide on Military Identification may be of use to you. It provides a number of different resources, including how to request service records from a number of national agencies around the world, as well as graphical aids to assist in deciphering rank, unit, and other forms of badges or insignia. While the users here may still be able to lend you more assistance, hopefully this will provide a good place to start!