Pretty much this IMO. I like the idea, for a night stand or desktop stand, but kind of pointless in a car.
Not sure who in their right mind would get into the car, want to take off their watch and charge it, and then put it back on before getting out of the car. The Apple Watch battery is designed to go all day and then you can charge it at home before either at night or in the morning, even if you wear it for sleep tracking. The watch charges up pretty quick.
Maybe I can see charging AirPods in the car, but again the battery life is really good on them that you would have be using the AirPods 24/7 in order to really drain the battery from the AirPods themselves and the case battery, if you really need to charge them in the car. If that were the case, I would just plug the USB-C to Lightning cable in and charge the AirPods case that way, and it'll probably charge faster anyways.