we always called them goozgogs too.
and it was a childhood sport to select a nice big one, pull out the plug, suck out the innards, re-inflate, reinsert the plug, and leave it in the bowl with the rest of them... happy days.
Of course it only worked on my grandfather's gooseberries, which were a large golden variety. The little underripe green bullets you usually get commercially are no good for such shenanigans.
Personally, I would be very suspicious of any one source giving an accurate indication of carbs. Ballpark, yes. Precise, no. There are a lot of different varieties out there, and they will all vary, plus then there is stage of ripeness, growing conditions, etc. etc.
I take the same view for all foods - tomatoes being a perfect example. I mean, watery, overinflated supermarket ones, or homegrown, sun ripened? No comparison.