The problem in english is that “for” can have multiple meanings in this case. It can mean the product is just meant to be used on item X or it can mean it intended to make the product more like X.
In this case, I’m confused because some people with curly hair hate it and want it straighter, so “for curly” hair might make it straightens or at least not make it curlier, while people with straight hair who DO want it curly would want a intentional product “for curly hair” to make their hair curly.
Which is it?
We have the same issue in French, but I would say that it depends on how positive the topic is. Dry skin is bad, so a product for dry skin will mean to take care of and hydrate it. For curly hair, it is a neutral description of the hair, so taking care of it would be more like caring them (maintaining the hydration, helping them curl, opposed to scraightening them). If you look for product that would help straightening curly hair, it would be marketized as “straightening curly hair”, not “for curly hair”.