After poking around the game and figuring out everything available to me (just some "research" and dwarf stat upgrades, both negligible contributions towards progress), it seems like the first "real" unlock is maybe housing at 300 depth? And timing it, it seems to be mining 5 depth (50 blocks) every minute. 300/5 = 60. 60 minutes.

Exactly one hour of waiting before I can maybe actually do something in the game doesn't inspire much confidence. If you're going to have an AI write your whole game for you, literally the very least you can do is playtest it yourself and do a few rounds of improvements first before subjecting the world to it.