Your low VIN seems to be consistent with how Tesla does rollouts where for Model 3 reservation holders owners might have the most relevant experience on this particular forum. An early reservation did give priority to orders and deliveries but only of the versions that were "easier" or "cost effective" for Tesla to complete, so early-reservation LR had priority over late-reservation LR, and then came early-reservation AWD then late-reservation AWD.Fairly low VIN (4xxx), took delivery in Jan 2018 with FSD… I'd like to note that while I'm glad to see they're actually starting to upgrade customer cars, I do wish they'd prioritize taking care of earlier buyers / HW 2.0 people first.
So similarly, looks like Tesla is trying to prioritize early buyers in this FSD retrofit process, so perhaps your low VIN 00#xxx ("Group 1") gave you priority over later Model 3 deliveries, and Tesla is in a better place to do HW2.5+MCU2 upgrades first. But yes, arguably Tesla has known for a long time that they'll need to do HW2.0->FSD upgrades too and could have figured it out before even starting HW2.0->FSD.