I have 1 questiion

They mean it as the full length, or purposely ambigious to allow a consumer to insunuate it, lol - whichever it may be. Just ignore those estimates once its growing. you observe and react. whether you predict an accurate length or not is irrelevant. if it's about planning, never assume it'll finish in 9-10 weeks as that's only going to happen with a very small, low-yielding plant. Also, for marketing purposes, even if it is accurate, it was the fastest plant they had and might be 1 out of 100 chance you get that... or 20% or whatever. 2-3 weeks of vege and 7-12 weeks of flower... it's really no different than a photoperiod as far as how long it takes to flower. You don't 'see' it enter flower unless your eyes are microscopes. flowower initiates ~7 days before you see developed preflowers at nodes.

when talking about autos its done as a whole timeline. eg from sprout to harvest. When talking about photos its done as a split timeline, the time when it is flipped into bloom 12/12

Best case - what breeder says , 9-10 weeks is all life span. In most cases with autos its 11-14 weeks , were flower takes 8-10 weeks. I had few fast buds plants which finished in 70 or less days since seed touched soil.

9-10 weeks from first sign of flower. Most autos generally give you 2-3 weeks of veg before you will see first flower, but that can vary whether it's a 8 week or 12 week auto. When it says "80 day auto" thays meant more from germination. If it only states flowering add 2-3 weeks more for veg.