First, .33 thick sounds really heavy. I assume these “dog tags” will be used for their bottle-opener function, and not so much worn around the neck?
Second, where the tongue goes under the edge of the cap to lift? That will erode pretty quickly. Aluminum opener vs. steel cap: Steel wins. Yes, it can work, because I’ve had an aluminum bottle opener before (even a plastic one with a steel insert right on the edge) but it eroded quickly, and I didn’t use it much. But that might be a smart business model, if you’re selling these!