I think the problem is more about the product market fit than youtube as a sales channel. I think your product is more aimed at an audience of geek-adult otaku

I think the problem is more about the product market fit than youtube as a sales channel. I think your product is more aimed at an audience of geek-adult otaku than a market of children interested in reviews of candy (so ordinary products that you can buy at the supermarket). In my opinion a strategy that would bring results is to do cross-marketing with similar niche sectors (manga lovers, otaku geek, japan lovers, animé fans, etc.). In my experience the japan culture lover is willing to spend constantly in this type of products. An idea could be to diversify the product (eg including Japanese magazines, gadgets, or other). So make more expensive packages and cheaper packages for different market segments. Sorry for my english :)