I will note some very important things with the structure of the Marvel Multiverse for a possible High 1-A rating.
This involves a unique story called Doctor Strange: Fall Sunrise and a bit of Immortal Thor. See in the Immortal Thor series when we see Toranos and Thor fighting there are things to not gloss over. It was mentioned the Yawning Void or Ginnungagap was mentioned to be the furthest shores of Eternity which would just refer to the Far Shore. This is established earlier in the Ultimates series when the Shaper of Worlds fell into Oblivion, he sawed what lay beyond supposedly the “Multiverse.” That's changed and my theory is that the Land we see in both Defenders: Beyond and Silver Surfer run which includes the Never Queen is still part of Eternity as one of three facets of the faces of existence. This would explain Al Ewing's intention both on his Twitter statement that the
Far Shore is part of Eternity as well as Immortal Thor describing it to be so.
Yes, I know you may be confused since the Ultimates series and Defenders: Beyond seemed to imply it exists outside of Eternity. However, that's the thing that was rectified during the final issue of Defenders: Beyond. The entirety of hierarchical cosmology is based on the fact that everything emanates from the Unknowable through the Four Worlds.
Eternity represents the whole of existence in the sense that he also holds the hierarchy we see which includes the crown of Creation which is about the House of Ideas. This puts in question whether Eternity or Yggdrasil is meant to encompass the whole of existence. That's honestly hard to answer, but I think that everything is a structural part of one accord within some sort of “truer Eternity” that may exist far above just the Omniversal version we see that seems to be disconnected when reaching the Void as we saw during the first issue of Defenders: Beyond.
For anyone confused, I think this was somewhat answered very ambiguously during the final issue of Defenders: Beyond. There was an Enigma to come and that crown was cast upon all over Creation as it was above all things. Well, Eternity knew of it as well as the One Above All who is just a representation of a magnitude of higher beings that are creators as well. This is mentioned when Blue Marvel questions what creates “Creation” which includes the House of Ideas and the form of the One Above All at that level. This would mean that Eternity and the Marvel Multiverse is far larger than just simply existing in the “World of Action” since the “World of Creation” as we see it contains even the crown of “Creation.” Where everything is connected in a hierarchical system hence why Al Ewing reaffirms the idea that Yggdrasil is akin to the Tree of Life in Kabbalah which also contains the Keter or the House of Ideas.
This brings me to my next idea. In the Doctor Strange series called Fall Sunrise. It was mentioned there was nothing which was “all” then a division happened, a sort of Dyad.
From the perfect formless nothing became dualistic in two parts: Bythos and Sophia. This represents the very nature of that perfection in a realm of pure and perfect ideas while Sophia represents the opposite end which is the Realm of Shapes which both encompasses the notion of what was “All that Is” as it is now.
It was explained that Bythos is the realm of pure ideas and that nothing becomes everything. In trying to perceive him do we see Sophia and the
Realm of Shapes which is just a shadow reflection of the Realm of Ideas. Sophia is literally “All That Is” which is also Bythos who is “All That Is” because their separation caused division, but they are the original existence of the “nothing” that was all “infinity” which is the “One” thing which is a reference to the One from Gnostics which the story is heavily centered around.
There are some things that the story gets wrong about the Gnostic aspect and are mixed around with older elements like Platonism, Neo-Platonism, and whatnot. For example, it was heavily notion that the Demiurge is the creator of the material world(world of shape) using the ideas of the pure and divine realm(world of ideas) while Sophia herself being an Aeon birthing this monster Creator-diety as oppose to the story treating Sophia as the mother of the Aeons. This is rather important because it establishes that the entirety of Creation as I put above is purely just a reflection of the pure and eternal realm of ideas. This means that the difference is in transcendence between Earth 616 Universe to Multiversal Eternity with the One Above All and the whole of Creation is in turn High 1-A for Byhtos and the realm of ideas.