So in the plans of this mod, there's the mention of a potential new faction, but from what I've read from the mod owner's recent comments, they seem uncertain on what kind of faction they could implement. So here's my take:

A faction of which the people that are part of it, are in fact victims of an old experiment related to genetics which was kept in secret by the Coalition, so they wouldn't look 100% human, instead they look like a mix of crawler / hammerhead / mudraptor / moloch / etc...and of course human.
Because of that, they would have benefits related to the creature they've been mutated into, such as a hardened skull for moloch people, or apendages in the back for hammerhead people, etc...

What would set them appart, would be that they aren't a sect, they don't venerate any god. Instead they are a community who pays respect to a former member, who made the exploit of liberating all the test subjects from the experiment before disappearing. It's said that this person was captured by the Coalition to be executed, so they honor him for his sacrifice.

Years pass, and new problems arise. Their presence to the public eyes leads to conflicts of racism, they're seen as inhuman horrors, ugly beings, etc...and the Coalition is corrupt enough to turn a blind eye towards that kind of injustice.

I could imagine their theme to take inspiration from Martin Luther King's movement, Rosa Parks' activism, and even Malcom X's supremacism for the more extreme cases.

People are welcome to bring up their thoughts about it, and bring up new ideas. They're even welcome to suggest changes and whatnot, or even something completely different too.