It doesn't matter, you have no way to power them in-flight.

The USB Portlets being discussed here are at the gate, not on the plane.

The grill being discussed can only be powered from USB, not charged from USB.

And the grill as discussed at the linked website (unfortunately there are no specs there) only says you can power it from your "home or office PC". No mention of a laptop, and I doubt the average laptop running off of batteries has enough current coming out of the USB port to run this. (There's a lot more USB power capacity in a tower PC than in a battery-powered laptop.)

(And even airlines that have power ports on the plane typically have a max of 75W from those power ports. Doesn't even support the most power-hungry laptops. I thus have some doubts it would support this grill...)

So you'll have to BBQ at the gate, not on the plane.