I can't speak for frostpunk 2, but frostpunk 1 was like a roguelike city simulator that teased some lore while beating your face in with disaster after disaster. It was novel for a bit, but i had zero interest in repeating that experience with frost punk 2.
I think narrative driven story rich games are great, but I don't think frostpunk fits into that category. Frost punk was a rogue-like with a theme.
https://www.youtube.com/watch?v=3kwK3m261Mw
Even when the stupendium song came out for frostpunk 2, i watched it with interest, but didn't really want to play the game again.
One of the big problems with NARRATIVE games, where there is only one narrative - is replayability. BG3 is a master-class in branching narrative and evolving worlds, more akin to a D&D session with a really, really, really, well prepared GM - so people play it over and over... and their friends seem them playing it, and it encourages them to try it.
I don't think i've ever seen any of my friends playing frostpunk
Even if you want to play a single player narrative game, there is no urgency to buy it, it is 100% perfect for patient gamers to wishlist and wait for a deep discount, there is no social urgency to play with friends like hell divers 2.
Steamdb:
It's unusual for the sequel to have less players