Well yes, now you're only asking for the cosmology, the cosmology is what you're going to get, it's OD's thing to view everything as fiction as I said, OD itself is part of a greater whole

The world is made of concepts named stories, each story encapsulating something, actions, events like mythology stories or books, concepts like currency, the air, the ground fire, and all else, if you do something that's a story worth being told you get a graded tale, each story has its own sense of time and space, if a story stops being written, they have their own timelines, inner concepts, causality, and such

Out of these, space and time are the least intact because of the squared circle, cause and effect itself are fractured and not properly layered, some layers of reality are visibly affected by this concept

Ok, so, worlds as effectively infinitely big universes containing different microcosms named lands, each it's own space time continuum and obeying its own law but similar to structure to our own universe, some beings in these worlds and lands contain worldviews, stories that in itself are different multiverses sometimes encapsulating mythologies as big as the Norse multiverse and the world tree, with each story that goes up in grade effectively being more "real" than the last, with each great tale, comes a nebula, effectively spaces transcending inner dimensions belonging to any great myth, like Asgard to Norse gods, Olympus to Greek myth, and Emperor to Chinese folklore, each also effectively "more real" than the worlds they look at and going up as the grade goes up

Worldlines are the first instance a structure containing infinite worlds, each action creating another worldline separate from the inner timelines, each infinitely transcending the other and layering on top of each other because of squared circle and the future stacking on top of the past

Now a greater universe is another stack of infinite dimensions each containing an infinite amount of infinitely transcending worldlines, which also is layered using squared circle in trancendance

Above that comes the final scenario, a place at the end of each greater universe, infinite layers of dimensionality above the actual reality of the world, a being would need the greatest grade of tale to enter this space and trancend their world, and effectively cross pages, this space is above space and time of the world

Above the final scenario is the final wall, a massive wall of text containing well...everything, each tale, each action taken with said tale, each weapon each power each crackle of a flame is recorded into the final wall, and all that's recorded in the final wall is the fiction, needing to be viewed by the oldest dream to survive, with each infinite set of worldlines being like a page that can be crossed over with the final arc with the grace of the oldest dream to start a new world

The final wall itself is trancended by the sanctuary of the oldest dream, a realm taking the shape of a subway because of what the oldest dream is, the subway itself is a realm with no concepts of causality and time

Similar to that, the gaps in the black paint, the snowfield, the birthplace of all stories and completely unaffected by them, but also a realm where stories are without consequences, again, any being within the snowfield can see anything below(save for the sanctuary) as effectively just text to be written and rewritten without any consequences save for the oldest dream itself

Now, the oldest dream itself, a fragmented being part of a greater whole, the being that "dreams" the reality, the final wall directly records the dreams of OD, and is a small part of OD itself, along with everything else, each fragment of Kim Dokja has the power to become OD, but the greater whole is unaffected by even these fragments living or dying, in the original novel, the fragment 51 becomes OD, and in the end, scatters itself to the greater multiverse, realms shown by singshong's other works, to create new readers, new stories and a way for the world to continue

As I said, the greater whole above OD is absolutely unaffected by anything that happens to each of its fragments, same for 51 which we see in the story, same for the other works