Well, bluetooth, wifi and cellular are radios, so my guess is it depends on what frequencies you wanna cover and how much extra you are willing to sacrifices in price & space.

Correct me if I’m wrong, but isnt broadcast done only manually? I.e. when you begin pairing? I guess it depends on device.

Correct, you won’t remember the time you got interrupted by an ad. You will however remember the name brand compared to no brand when you see them, and are already conditioned to associate brand with quality and worth.