Through a chance piece of design, the leading power pack in terms of energy density is made by / branded on behalf of Haribo, a confectionary company:

https://www.ultralightnerd.com/index.php/2025/06/26/haribo-m...

What’s interesting is, like the other products, it was designed and marketed for one purpose but has become very popular for another. (Although in this case it could well just be a fashion, especially given how uniquely identifiable the product is.)