This is a FASCINATING topic. Anything relating to qualia, honestly, is. My understanding on a blind person seeing color under hallucinagens is, it’d depend on why they’re blind. If it’s something with the eye or optic nerve, then the brain, the thing that actually MAKES the color, should still be able to produce them, but if that area of the brain is damaged, then it’d be a lot less likely for them to see any color.

Also consider, if they do see color, but have never seen the world before, they won’t have any way to map color to object. So they may see a stop sign (or their interpretation of it, more like) and it may be in color, but essentially random. Now how do we know two people’s ‘red’ is the same color? All of this is absolutely fascinating to me.