This.

It's worth noting that while Germany was not 'unified' until the 19th century, the regions of Germany had long histories together both of war and cooperation and political connection. The Holy Roman Empire had a long history and its final phases were integral to the formation of Germany.

It's not that Germany was more unified exactly, so much that Germany came into being with a history that made unification into a nation state a smoother process.

Italy in contrast had a long history of division, factional regionalism, and was rapidly unified without that same history of cooperation and political partnership. Its history of distinct and independent city states, dukedoms, and kingdoms didn't carry the same experience of working together into modern Italy like modern Germany.

I guess we could say Germany was more unified, but I think that boils the history down a bit too much.