I can't tell if you're being sarcastic or not but:
1. It would be easier to use than a pin because it's connected to your hand. You can press it without anyone knowing that you are pressing it. You can presse it with a single hand in a comfortable motion. It doesn't fall around or look weird on your body. It also just be a ring because it only needs to connect over short-range to your phone.
2. Earbuds give you privacy, volume control, good mic quality, better battery life. Also again they are slightly more subtle than a large pin.
3. You don't make these stand alone hardware. You just have them talk to your phone and have it handle networking, camera, compute as needed.
Like a pin. With AI. And it would talk to you like a human, so we could call it the Humane AI Pin.
How did nobody thought about that?