For something like that to work, it would still need enough processing power to not only hold that data, small as it may be, but also transmit it via some fashion, either through Bluetooth, wifi, radio, or some other form of technology. If it is an active transmitter, even if it were to hold a single byte of data, the technology doesn’t exist to function at that capacity at that size

If it were a passive transmitter, essentially what you’re suggesting would be similar to a barcode tattoo, which is no different than any carried vaccine card or general ID that would be scanned, and then cross checked with all your data. So, there’s no use developing it since you already flash your ID at any doctors office, bar, bank, and voting booth. No technology currently exist that would be able to read that data on the fly, especially if you would block the signal by something as simple as a T-shirt.

I promise you, what you’re suggesting does not exist, and will not exist any time soon.