Yep, they are out there, they range any where from 20 bucks to 50 bucks, I've bought one a couple months ago for 40 bucks I keep it on my golf back for when I'm out on the course.
Most of them are actually external battery packs with a small solar panel strapped on to extend the charge on the batteries. They are solar powered in name only but people are easily greenwashed.
They're fine for occasional emergency use or to extend the charge on your phone but they are not for use as the primary charger. There are camping ones that are more expensive and usually fold out to give you much larger solar panels. If you have nothing else to charge with, they're better than nothing.