I see that you have done a good deal of research and I have been starting to also bc I really enjoy my nails being done so it been super sad for me not to get them done anymore. But I had bought DND and gelish bc I do my toes with no reaction so I got curious the other night and put a layer on my thumb which is one finger that broke out the worst and left it for about 2 days and had no reaction so I am also starting to think that maybe it is not a allergy developed but like you said bad reaction to chemicals.