Delivery time at least 5 days... will be tight until Friday ;-)....

"one with accu"
As can be seen in picture 3, the device works with a mains adapter. Special powerbanks with an AC output exist, such as the following, to achieve the (as I understand it) desired solution:
Xtorm AL390 (18000mAh)
("Aku" is spelled with two k's, by the way)