He must have just thought about it for a while, or we're over anolyzing. It's interesting how the underlying structure of Elder Scrollsverse is so different from other fantasy universes. At first glance, you could assume most of it is a reskinned Tolkien series with some dualism thrown in. The differences are bigger though.

The Tolkien Legendarium is fundamentally a Christian worldview. There is an all-powerful but benevolent Creator who knows what is right. Not everyone understands his reasons, but they are what is best. The antagonist is someone who is greedy and prideful, and tries to steal glory for himself. The problem is that he was not meant for such glory, so he is doomed to fail. All the themes point towards the self as fundamentally flawed, and the only true happiness is in carrying out the plan God gave you.

Elder Scrolls is almost the opposite. There is no divine plan. The central creator figure is either unaware of his dream or too insane to really interact with it. It dreams because it is desperate, not for the sake of creating. There is a greater degree of random chance. The person who deviates from the collective will(Lorkhan) is portrayed as a good guy by many "good" factions, as opposed to Melkor in the Silmarillion. The self is portrayed as something good. Instead of discouraging selfishness, it is encouraged by concepts like CHIM.

Because, I assume, the Netchiman's Wife is the utility that gives birth to Vivec, who in turn creates the God-Amalgam of ALMSIVI?

But how does that make the netchiman's wife = heart of lorkhan? The god Vivec was born from the hearts power, but before that he wasn't a god afaik. Just meant to be. If there is anything I'm missing or misinterpreting please let me know.

The 36 Lessons are not Vehk's mortal history. They describe Vehk's life as a god--after all, the Battle of Red Mountain doesn't appear until the very end of the series, but ALMSIVI is divine through the whole thing. The Lessons have been interpreted as ALMSIVI literally rewriting their history with the power of the Heart and a directed Dragon Break. Others have simply dismissed it as a piece of fiction, nothing more than propaganda that Vivec produced to make himself appear more important. It remains important to us as a guide to Dunmeri metaphysics, but not as a factual representation of Vehk's life prior to his godhood (even if it is literally true, it nonetheless is the kind of "true" that was imposed on history after the fact through divine intervention; as I said before, in no place in the Lessons is Vehk not a god).

Thanks. I think I like the explanation regarding the directed dragonbreak. This explains indeed how Vehk has been divine and part of the triune from day one.
This has been a thing that had me confused for some time. Are there any hints or sources as to how/if they did this further in the sermons? If so I'll probably get to it later myself. Want to do this step by step to prevent regular brainfarts.

I don't know either, not really. I'm just hoping 'hawks elaborates.

I don't feel like it is a good connection. I just feel that the Heart was an incredible important part in Vehk's character, the Stone that shaped him into what he is, what made him go from just a petty and power hungry mortal to a living god and, ultimately, to a ruling king of the world. The Netchiman's Wife was an expendable womb, a worthless tool to them.

Ayem and Seht are Vehk's makers, hir mother and hir father. Their apotheosis was an act of self creation, they created themselves. ALMSIVI created itself, and so each member created the others.

I can see why it looks like the Heart. After Vivec achieved CHIM, it was expendable, and it was the catalyst in Vehk's making. I personally don't like the way it is presented though.

Ill give my interpretation. The first sermon is describing his birth into godhood. Look at it in a way that the 3 ascended at different but at the same time...
Ayem goes to village of netch (dwermer) first as the representation of plots. This could hint that SHE was the one who came up with the idea. The netchwoman is the heart. She is at the heart using the tools or just basically doing her part of the ritual. Inside the heart being, vivec is being combined/digested/etc by the heart. At this time, Vivec the mortal is destroyed and Vivec the god is being formed.
The gills and milk fingers is an interpretation of a "change" of the heart or inside the heart. The waters could very well be the waters of oblivion.
Sortha Sil part in the process and fishes the "idea" or "force" of vivec out of the waters. The form of vivec is still incased and being formed by the heart in our world, but outside our plane what is fished up is a cocoon into the different planes of oblivion.
The teachings and not whatnot of the creatures and daedra gathered is because of how abnornal this situation is imo.

That's off the top of my mind and a very fast and quick explanation without much meat. I'm still noobie at lore but it does make a lot of sense seeing how the heart is what created vivec and if u see it as a step by step process that ayem and seht did the work with the tools while he ascended.

The heart is a womb and ayem and seht are his parents due to them being the ones to use the tools during or to make his ascendtion.