Agreed, this is a good solution and it works well for the Mavic 3 battery which has a special cable. There is also a Power 500 which is basically half the size.
I've got DJI Power 1000 that would definitely do the job for you, but it would be a handful to carry around with you. They even make special cables to fast charge most of their drone models. I say most because they don't make a cable for the...