There is no strain that will grow from seed to harvest in 7 weeks.......more like 12-14 weeks minimum, no matter what the breeders say.
4 weeks of veg and 8 weeks of flowering is about as fast as it gets.
None are 7 weeks from seed to finish from seed to flower in around 5/7 weeks and then flower is 2 weeks stretch and then probably 7/11 weeks flowering so around 14 weeks min I would say