Galactus (Marvel comics) in the Warhammer 40k universe. What happens?

[Cleric of Hell’s Brigade]

The Choas Gods get a new threat. Galactus arrives in the 40k universe, intent on ending the threat of the Chaos Gods and bring order to this universe.

How does his arrival change things? Can he alone make the WK40 a ‘better’ place and end all the conflict, bring order out of the madness, endless war, and chaos? How do the Chaos Gods, the Emperor, the various Xeno races, and everyone else react when he appears?

Bonus Scenario: He arrives and, with intent to take over but not be so blatant in announcing his presence, has made an alliance with Roboute Guilliman (in whatever form that becomes, be it making him a Herald or whatever). With a foothold and knowledge given him by Roboute, does that make any difference?

[Nik Hasta]

Why would Galactus want to bring order?

Galactus' whole deal is that he's notionally beyond the concepts of morality and is a personification of a force that balances the universe between Infinity and Eternity.

He'd likely make it a point to go after the Tyrannids, they devastate the life bearing planets he needs to sustain himself so once he figures out what they are, he likely spends the next couple of centuries wiping them off the face of the galactic neighbourhood.

[Shellhead]

Galactus: [BELCH] I CAN'T BELIEVE I ATE THE WHOLE THING.

Herald: [nervously clears throat] So, uh, back to the 616 now?

[Cleric of Hell’s Brigade]

Why would Galactus want to bring order?

Galactus' whole deal is that he's notionally beyond the concepts of morality and is a personification of a force that balances the universe between Infinity and Eternity.

He'd likely make it a point to go after the Tyrannids, they devastate the life bearing planets he needs to sustain himself so once he figures out what they are, he likely spends the next couple of centuries wiping them off the face of the galactic neighbourhood.

Poorly worded, perhaps. Mostly because I would presume all that chaos and instability would make it more difficult for him to exist there/feed.

[Lord Falcon]

You know how the WH40k universe is on the clock because each of the three main Tyranid hive fleets thus far have just been tiny scouting units of a massive hive fleet that could absorb every munition in the Imperium and keep on trucking without a problem? Galactus is like if that hive fleet were condensed into a single entity and then magnified by several orders of tech and cosmic power. Galactus would eat the Tyranids. He would eat the Orks. He would eat humanity. He'd probably manage to do it in a relatively sustainable way, but he'd do it and there's nothing any of the races can really do to stop him. Warhammer 40000 woudl probably overall become a better place by virtue of not dying to massive Tyranid endgame. Not sure Galactus could actually end the Chaos Gods though. I reckon he might find a way to close the Eye of Terror, but that's just conjecture.

[Postmania]

The main factions kind of top out at planet busting so none of them are doing anything to him.

So it comes down to the Gods (Necron, C'tan, Gork & Mork), which don't really have the feats to say anything here unless I'm mistaken

Of course if it took place in a WH40K story the vagueness works in their favor as they can always pull out WarpForged Chaos GodGun 2000 out of somewhere and do something in a story, but that's neither canon nor really implied nor relevant to Rumbles unless I'm missing something big for the WH40Kverse