Sure, a speaker can serve as a microphone, but only if the electronics is made to use it that way. Such is not the case for my TV. Not only that, is not capable of sending data upstream either. It must be used with a media source since it does not contain one. (It is not a recent model.)
I couldn’t even begin to know where to look in a TV of today.
Howard Sams taught me everything I know about tv circuitry.
I do know that unless one is able to decode the fantastically small circuits in a IC chip, there is no way to know just WHAT the thing is ‘capable’ of doing.