If you've got a keyboard related product that you're looking to advertise, then instagram and twitter are not... I was about to say, "not the best places to go," but I honestly have no idea who uses those. As far as I know they're primarily for porn and racism, but maybe also for keyboards?
Regardless, there are some youtube personalities who get a degree of attention. If you want a list of the prominent ones, search for 'Youtube GMMK Pro review.' Glorious seems to have sent samples to absolutely everyone, so that's probably a good way to figure out who's talking about these things.