I have colonies that overwintered, but they're not technically sitting in nuc boxes.
I don't even think it's possible to overwinter a colony in a single nuc box in my location.
Local beekeepers have told me they sell overwintered nucs as colonies that WERE double or triples, and then condensed down to 1 nuc box for the sale in the spring. Using the overwintered queen and her brood etc.
What's your opinion?