Since we can't find Xiaomi ZMI 20000mAh powerbank anywhere, this Kogan one comes in handy. It boasts a respectable 36W USB-C PD output and well enough to charge Macbook Pro 13's albeit rather slowly. Even though Kogan's description says that this only output 36 Watts, 20V 2A is mentioned on the powerbank itself as seen in the pictures. So it might even output 40 Watts but input maximum is 20V 1.8A (36W).
Create a new Kogan account to get it for $39. If you can't be bothered its available on Ebay as well for $47.41 (Thanks O O)- https://www.ebay.com.au/itm/Kogan-Ultra-Fast-20-000mAh-Power...
Description copied from kogan -
Ultra fast charge with 36W input and output
Can charge laptop!
Massive 20,000mAh capacity
Multiple ports for rapid charging of up to 5 devices at once
Compact, portable and lightweight
Durable and efficient lithium polymer battery