With all due respect, technically speaking? Apart from the serve, technically what does Kyrgios better not only than Zverev, but better than any top 50 (or even top 100) player? The answer is nothing.
Kyrgios is a clutch player, which is a giant asset, and all credit to him. He is big, strong, and fast. And has very quick reflexes. But his lack of technique is glaring. I bet he knows that quite well, as he seems to be a smart guy.
I am answering to your post, but I am actually answering to whole flow of comments about Kyrgios, and I promised myself that I would keep out of this conversation. My honest opinion is that most people in fact never ever saw an entire Kyrgios match, maybe just the ones against their favorite players. It seems that all talk derives from the (very short) highlight clips out there.