Review Detail of PsyLoRD in The Plague Father

I love W40k but you're dead wrong. Because of how well the stories/the setting in 40K are described we know for sure that they're Galactic level at best. Literally no influence outside of the milkyway galaxy. It's why the Tyranids are a thing, outsiders from their own galactic slice (who presumably took over their own) reaching for other galaxies

And there's even a fan theory that the Tyranids are fleeing something so yeah, far from being the top of the top.

As a note to your comment for other readers, the 5 Great Gods in Marvel (Lady Death, Eternity, Infinity, Oblivion, and Galactus) are literal embodiments of the universe responsible for different concepts - including (but not limited to) life, death, space, time, reality, the universe's expansion, or the rebirth of the universe, and are thus individually capable of welding power comparable to that of an entire universe in raw power, possibly higher if their concepts can work independently of their own universe.