Seeing good results with the Macbook, we will observe how the GoPro Supercharger sets up a similar power contract with the Dell XPS 12 9250 2-in-1 Laptop which also supports USB Power Delivery charging.
The GoPro Supercharger starts off negotiation over USB Power Delivery by offering its source capabilities of 15 watts (5 volts @ 3 amps), 16.5 watts (5.5 volts @ 3 amps), and 20 watts (12 volts @ 1.67 amps). The PC proceeds to request 4.5 watts (5 volts @ 0.9 amps) from the charger which it accepts.
Despite the USB Power Delivery negotiation being completed, for some reason, the Dell XPS 12 9250 2-in-1 Laptop does not pull any current from the Dell XPS 12 9250 2-in-1 Laptop with the battery fully drained.
Unfortunately, we were unable to charge the Dell XPS 12 9250 2-in-1 Laptop with the GoPro Supercharger.