This is just going to be a short theory or some mini pondering thoughts of mine at the moment on ways to ascend to power/godhood/divinity and anything that might relate to the former.

Keep in mind that I may not be objectively right (based on the various info and common ground abstractions of the TES:Lore)

Generally I think lore is a state of mind, so to the most of our extent we can just have fun sharing our thoughts. So for the tyrannical loremongers out there who think they have full grasp of the objective you're the same as I a fellow mortal bound by our greatest & most coherent and incoherent flaw to the universe which is conditional reasoning. It's after all what's called "the human condition".

Anyways before I get into real world (like I can ever be certain this truly is) metaphysics and philosophy stuff, I'd like to add some theories of mine of how one can achieve this.

Ignore the wall of text below if you want to get to the main point.

^ Forgive my wall of text above, I just really needed to make a point as to why I'd strongly like to rule out CHIM as a method.. It's just ties up too much with even our real world philosophy and coheres & incoheres too much with our reasoning, it isn't in the common ground of what us petty humans can claim understand. It just creates paradoxes, not that fun to discuss in general, at least for most people.

Okay so here are my two theories:

One possible way to gain power to match a Daedra (more preferably) or Aedra is that if we look at the life and existence of Talos (Tiber Septim) and his debatable & so called "ascent to godhood" through deeds/actions or unbeknownst reasons.

Short & simply, the only theory I have is that Talos being dragonborn. Since dragons are known to be children of the akatosh/sky, and Akatosh is an Aedra, plus another theory of mine on how a Dragonborn can absorb souls and truly void a dragons existence (which are lesser forms of akatosh himself, again another theory of mine is that dragons DO NOT HAVE the dragon blood of akatosh, dragons are more like clones of akatosh, but with each clones Akatosh's power becomes transfered/splits into each dragon.) Now the dragonborn is different, the dragonborn may have what is so called the dragonblood of akatosh himself, I say this because there might be some there who are not convinced with Queen Alessia's blood inheritance from akatosh.

From what I know of no other dragonborn of the previous eras of past has been speculated and believed as much as Talos' ability to ascend to godhood.

The best possible method of Talos' ascent to godhood, may as well be through the souls of dragon.

Let's look at the closest link of Akatosh and a Dragonborn = blood.

Here's a theory that also has to be true for Talos' godhood to be at least plausible:

Akatosh should be able to absorb back his Dragon chilldren, regaining part of his Aedric power back. Since he created them by splitting his power it'd only make sense.

If the above is true it may as well lead to another theory of mine: (Secret of Akatosh & the Aedra)

Why did Akatosh give birth or split his power to create lesser forms of himself?

It may reveal as to why the Aedra desire worship.. Since there are reports from lore that Magnus tricked/decieved the Aedra into the creation of Nirn thus giving themselves to become the "bones" of Nirn they in turn became part of Nirn and has become less powerful than the Daedra who did not partake in the creation of Nirn.

They may desire worship and may compete (at least to some extent in my theory) because their lost powers flows in Nirn and is what sustains it, those who worship them may as well restore part of that power through various forms of interactions & ways.

So Why did Akatosh give birth or split his power to create lesser forms of himself (Dragons)?

If all the above is true then there's a strong possibility that this one is true:

He did it because he planned and believed that his lesser forms would wreak some form of havok (or some sort of method of gaining attention) for akatosh for the mortals of Nirn to FEAR the Dragons and WORSHIP them, thus gaining worshipers and followers of Akatosh to restore his Aedric power.

^The reason he would do that is that again BECAUSE AKATOSH KNOWS he can call back/merge his former beings of creation (the dragons) to restore his power.

This gives birth to another theory of mine: TADAA!

Another theory of mine is that Akatosh cannot fully control his lesser forms, they have a part or "small" mind of their own, I guess this can be said because of dragons having forms "uniqueness", but to some extent he may be able to influence them and control them or they either serve his purpose in some way.

BUT

ALDUIN - FIRST BORN OF AKATOSH.

^Alduin now I have a lot of speculations on his creation, but it could only be either two things:

His mind of his own was either an accident of Akatosh, his power and mind of his own a disaster.

OR

A purpose of placeholder plan for merging of Akatosh and Alduin as one entity at the so called end of Nirn where the stiff Aedra Akatosh will grow weary of serving Nirn and will break out of it once he regains enough Aedric power (again another theory)

Why Alduin's soul wasn't devoured by the first dragonborn who faced and "defeated" him?

I'm also not quite solid on my theories on this one but I'm going to go back in time:

For one of the most interesting events for me:

Why did Kyne help mortals during the dragonwar?

It may as well be due to another theory of mine, that is the Aedra in all their "righteous" forms are to some extent or full extent power hungry. Kynareth may have plotted with Paarthunax or just by her aedric self taught the Thu'um to mortals. <- which in turn could turn out to be another plausible theory, all the Aedra know the Thu'um and can gift them to mortals, does this mean that the true form of the divine Aedras are all dragons-like entities?

On to the Dragonborn and his purpose:

Why did Akatosh bestow his dragonblood, to what mortals would be called the Dragonborn? Simple same way he created lesser forms of himself.

Equation = power return expectation.

Finale:

The only way Talos could've been an Aedra is through a means that might be a result of minor miscalculation on Akatosh's part or placebo like effect.

You see what if it were that the Dragonborn of an era would so quickly rise to power (both divine, and mundane power) as fluidly and as the same or better conditions of the reign of Tiber Septim.

WHAT IF: Tiber Septim's growth to power has been an error of maximum output calculation of Akatosh himself, what if Tiber Septim ABOSORBED enough DRAGON SOULS to EQUAL or EXCEED Akatosh's current Aedric power.

BUT HOW MUCH SOULS WOULD IT TAKE?

A good example is what I stated above, EQUAL or ABOVE Akotsh himself. If was indeed Alduin was a miscalculation on Akatosh's part then it may as well just true. Akatosh couldn't absorb/regain back his power from the Dragonborn that equaled his own, thus the Dragonborn shall ascend to godhood.

The problem now is, what is a mortal-divine hybrid capable of? Where do they go after physical death? Do they become bones that hold Nirn as well?

Here's another theory of mine about the Aedra:

They maybe in theory weaker than their Daedric counterparts, but as an Aedra focused on by worship of the mortals of Nirn they will be a dozen times stronger than a Daedra can handle. Which may prove how even only the Avatar of Akatosh could banish/defeat Mehrunes' 1st coming to tamriel back in the OB crisis.

My second theory is a bit more unlikely but interesting for me as I'm particularly fond of vampires:

This one's really simple since I think vampires in Tamriel are more frail than the fiction/lore/philosophy of what we have in the real world.

Basically we have a special vampire, not specially attuned (through some way) to Molag Bal. He/she has the ability to feed of other vampires, he/she becomes as powerful as the first vampire made by molag bal (according to lore) then finally his/her eyes glow with reflection coldharbour's plane. Then the vampire now seeks to ultimately face off and destroy Molag Bal and in the process absorb his power through vampirism, The end.

^Yes it's quite cheesy, but I like the story I use it for my vampire characters' backstories. Okay I guess for this to at least be plausible, the first vampire Molag bal created must have been granted at least half of his power. If not then it could still be possible only if a vampire's power gets increased through feeding on mortals on Nirn, with a bloodlust enough to decimate an entire region's population then a vampire could indeed stand a chance against Molag Bal himself.

It may also prove that there really is nothing about Aedras & Daedras having full invincibility, only that power transfers from one entity trough another. Which can be attested by the creation of Nirn itself.