Devouring Swarm: Eaten. Their old territory is a fucking mess now but I was able to simply split off the worlds I conquered into a vassal, which will convert into the final specialist vassal type and get me the achievement in 500 days. Bazinga
Breakfast Cult is great. I wasn't expecting it to be
a big thing when I started and I'm honestly surprised this many people decided they vibe with it, but you know what, sure
My next potential vassals are the Space Pirates. Pros: After losing a war to the Purifiers they've been reduced to one planet, making them easy to vassalise. Cons: Their last planet is adjacent to -two- genocidal empires! Great!!