Forgive me if I'm interpreting you incorrectly, but I'm not sure you understand what gate-checked means.

Yes, it would be allowed in hand luggage, but if that luggage happens to be taken away from you at the gate (because there's not enough room in the cabin / overhead bins, et al.), it would then be 'gate checked' (hand luggage which becomes checked luggage at the gate). That's when you'd have a problem, because the battery-powered device shouldn't be in checked baggage, regardless of where if becomes checked baggage.