I'd prefer a one word word for to-be-named(or maybe not) puppies, I'm not gonna lie I think unnamed is the best word for it, because it implies that they are to be named, not to mention it's easy to read as a name in it of itself. Nameless is fine also but it doesn't have the positives of unnamed, or some other option. I just don't want it to be two words by default, I'm not a fan.