Re: smartphones?
An Apple watch can have its own phone connection these days. I guess you could get smaller than that. If you search for things like "GSM smart pen", you can get an idea of what you can hide a phone inside.
An Apple watch can have its own phone connection these days. I guess you could get smaller than that. If you search for things like "GSM smart pen", you can get an idea of what you can hide a phone inside.