Snowpiercer was originally a set of three graphic novels done by Casterman in French and Titan in English.
1: The Escape
2: The Explorers
3: Terminus
Then they launched a prequel series which was also supposed to run 3 volumes:
1: Extinction
2: Apocalypse
3: Annihilation
That 3rd book was supposed to be out in 2021? I guess it was Covid-Delayed?
It came out October 10, 2023 in France, but for some reason is impossible to buy. It’s out of stock everywhere.