I define consciousness as the sense that it’s like something to be

“Like” just means “akin to” and “to be” just means “reality.” I do not see why we would define “consciousness” to be “akin to reality.” Sure, if we define “consciousness” to be akin to reality, then we aren’t going to be able to explain how the brain “gives rise to it,” because you would be demanding that we explain how the brain gives rise to reality, which makes no sense, the brain doesn’t create reality. You could then conclude that consciousness is the basis of reality, but only because you defined it to be reality, not because you would have proved anything particularly interesting.

that it feels like something from the subjective perspective of an organism

Why is the perspective of the subject singled out as particularly important? A perspective is just a frame of reference, and you can define a frame of reference in relation to anything, I fail to see why the subject’s would somehow require a special explanation.

I’d argue it’s the only thing in the universe that cannot be an illusion.

Obviously reality cannot be an illusion by definition.

Even if we were living in a simulation where everything was fake, it would still feel like something to be simulated.

If we were in a simulation, everything would not be “fake,” because the simulation would still be a real part of nature. Reality cannot be fake, that’s a contradiction in terms.

That’s all there is: the subjective experience of life happening

Oxford Languages defines “experience” as a noun as “practical contact with” and as a verb “encounter or undergo.” Again, you are singling out the subject as particularly important and not giving a reason as to why. Experience just basically refers to having something happen to something else. A rock can experience erosion in the rain, a thermometer can experience fluctuations in temperature. I can experience a traumatic event, or I can experience some delicious food. I, again, do not see why we should single out the subject as requiring a special explanation.

There’s no “you” at the center of the experience, no point in your brain where everything comes together and a self resides.

That’s just how perspectives work broski. If you have a beaker filled with a substance and you want to measure just the mass of the substance, you can place the beaker on the scale first while it is empty and then tare the scale, and then put the substance in the beaker and you will get the mass of just the substance on its own. That is because you are centering the coordinate system, the reference frame, upon the beaker, so it acts as the zero-point of the system, and effectively disappears from the picture.

As another analogy, consider two billiard balls colliding with each other in empty space and then bouncing off of each other. Conceiving of this only makes sense from the reference frame of a third system, because if you adopt the reference frame of one of the two billiard balls, then its position would always be 0, and thus could not change, and thus its velocity could not change, either, it would always be 0. from the reference frame of one of the two billiard balls, it is not moving at all, and it is solely the other one that comes towards it and bounces off of it. Because it is not moving, its velocity cannot be changed either as a result of the collision, only the other ball’s velocity can be changed.

The object chosen as the basis of the reference frame effectively disappears from the picture by being used as the zero-point of the system. The fact it disappears means it can no longer “interact” with anything either, because its properties cannot ever be altered. From the perspective of a third observer, you can see that the reason I see a tree is because the light from the tree is interacting with my eyeballs. But from my own perspective, I cannot see my own eyeball, because it is the zero-point of the system and thus effectively has no properties. All I see is the tree on its own. Whatever system is being used as the basis of your coordinate system can never participate in an interaction, it cannot even have properties at all, except through reflection.

The feeling of self is just an appearance within the prior condition of consciousness.

Self-hood is a very different thing than what you have talked thus far. The self is something derived a posteriori through reflection, and is essential to our mental models of how the world works.