I have the Anker 737 Powercore 24k powerbank, which is a 24.000mAh power bank capable of charging and discharging with 140w, which makes it a perfect Steam Deck powerbank as it can charge itself super quickly while still expanding the Steam Deck's portability massively.

Can charge the powerbank in 1 hour or less, while adding over 10 hours of gameplay to the deck - or more, depending on how power hungry the game is.