I'm in a similar zone but further south and kept a pomegranate in large container. I had Nana which is smaller. It did well and fruited.
I was away from home when we had that horrible freeze a couple of years ago. It was not protected and didn't survive.
Were I to give advice, I would suggest a similar small pomegranate and a container that you can move in or provide freeze protection as the roots are more vulnerable in the container. Good luck with it.
