Yes, it really works! I thought it was a fun idea! I'm just a hobbyist but I have an Etsy store. There is an 1AA model and 2AA model. It squeezes out the last bit of juice from your "dead" AA cells to give you light in an emergency. When the AA battery won't work in other devices, it will work here.
https://www.etsy.com/shop/Electronicals
https://www.etsy.com/shop/Electronicals