[X] TEKKET
[X] The Destroyers
[X] The God Machines
Clearly Mechanicus inspired. However, despite the obvious obsession with SV to be very much obsessed with technology, I find that these three choices in particular form a very cohesive story unlike any of the other ones combined.
By putting them together we get this.
The Tekket are clearly born on either a dumping ground for the the Mechanicus or an ancient long deserted Forge World. However, their entire existed is instead owed towards the C'tan here. Why are these…Shards? Full? I'm going to assume shards as that makes the most sense. Shards here? Unknowable. But they are very possibly the creators of the species as a whole. But that doesn't need to be the case, instead it forms a narrative here.
It gives purpose to the Destroyer Cult, beyond just being here to destroy all life, as they do. They were here for the God Machines. And likely their discovery by the Tekket was because of the Necrons going after them more than they were going after the Tekket, which explains how they even survived the Destroyer Cult to begin with, because they defiantly wouldn't have survived long if they were.
Something went wrong, either they woke them up while trying to throw them into a Pokeball or the Tekket interviewed in hopes of denying them whatever the hell they wanted. Regardless, C'tan woke up and did as C'tan do. The Machine Gods origin implies that there was a lot of them. With only these three remaining awake. To me this sounds a lot more like three ancient C'tan were blown up on this world during the War in Heaven. And all the pieces remained here for whatever reason. Who knows, it's up to Bird to make the story.
Regardless, it forms a cohesive narrative for who, what, where, and why. I like it either way.