I took a punt on this recently, not the most powerful out there but has fast 18w fast charge, it will easily charge the Mavic Mini batteries in their hub, it also has the much more convenient USB C as input.
As others have already said, my main go to are Anker, they do stuff that will power a MacBook so I’m sure the osmo will be no problem, Ive previously used the small mini Ankers to power a gopro on timelapse duty.