Since we have confirmed that the Nintendo Switch AC Adapter can successfully charge the Huawei MateBook from a well charged battery, we now find out how well both the charger and PC perform over USB Power Delivery when the PC's battery is at 4%.
Plugging in the Nintendo Switch AC Adapter to the USB Type-C port on the Huawei MateBook, we can see the Nintendo charger advertises its source capabilities of 7.5 watts (5 volts @ 1.5 amps) and 39 watts (15 volts @ 2.6 amps) over USB Power Delivery.
At first the Huawei MateBook is observed to request 15 watts (15 volts @ 1 amps) from the Nintendo Switch AC Adapter.
After the Nintendo charger provides the requested 15 watts, the Huawei MateBook eventually takes full advantage of the 39 watts (15 volts @ 2.6 amps) offered by the charger.
We further observe that the Nintendo Switch AC Adapter actually supplies around 25.1 watts (14.8 volts @ 1.7 amps) of charging to the Huawei MateBook to confirm that the charger is also able to use USB Power Delivery to charge the PC from 4% battery.