So, the author introduces a set of power levels:

1. Skyfather

Pretty much Odin's level, they're capable of destroying entire planets, travel time, and reviving the dead. There are no secrets in front of them.

2. Dimensional Lords

The same level as Skyfather, just the hell variant, Mephisto, etc. Cyttorak is one of those dimensional lords, but his power far exceeds Skyfathers.

3. Single Universe

In Guardians of the Galaxy Vol.2, Star lord's father, Ego, is on the single-universe level. Basically Celestials, and probably Watchers.

4. Multiversal

The most well-known Multiversal gods are the 5 who created the Universe, Eternity, Infinity, Death, Oblivion, and yes, even Galactus (Only when he's full, which is never).

5. Megaversal

Nemesis is Megaversal, you know, she broke into 7 infinity stones in the comics, though the 7th stone was called the Ego Gem, appearing in Avengers/Ultraverse Issue #1 (1995). I think the Living Tribunal is also Mageversal, though you're welcome to debate.

6. One Above All

Welp, pretty much the ceiling of comic book power.