Not sure apparel products added to a crowded market would have enough differentiation to make a decent margin for Anker, so I'd be thinking of some innovation and merging of products. Then you have the usual problem of if you merge tech into apparel as tech improves faster than apparel and can fails faster than apparel you'd have that apparel appear old tech fairly soon.
Probably the thing I'd like is a trouser with Qi wireless charging sleeve in the pocket with say a belt which contains a battery and you drop your phone into your pocket and it slowly charges. Yes I know most phones dont have Qi but you can slip a receiver under a case and many use a case.
A shirt with small speakers built into the ends of the neck collar so you can hear someone and hold a conversation without separate headphones.
i'd like to see a merger of the LC40 with the Powercore+ mini for a bright torched combined with a rechargeable battery, say with a screw-off cap to make it waterproof.
Trickle charge solar case. Not sure if you'd get a worthwhile current from such a necessarily small solar panel and the weight of solar often renders it pointless, but if say you have a folio case which opened up to double the solar size?