Interesting stuff but I don't see how we could be living in a 2D universe without everything being flat
The observer breaks down to minimum of 2-dimensions. The maximum amount of "storable information" in any given space breaks down to the surface area not the volume of the given space. A black Hole breaks down to a membrane "flat surface". If you could sit on a light-photon, you would only get a 2-D view. We still live in a 3-D space, but to understand it fully, you slice it up.
When I break it all down visually... 2-D observer plane makes most sense. Visually you could imagine it like a Holographic flip-book
.... If you can picture that.... Each page would contain a 3-D Hologram - each flip of the page ( a new moment in time) would create the illusion of motion,time & depth. This is how the brain/mind might construct reality theoretically speaking. You still have a 3rd-dimension - its a page flip.
insofar as the brain is a holographic receiver
The brain needs to have a workable mechanism to interact with reality, the Holographic brain principle makes a lot of sense - when you consider brain waves (communication), light waves (eye), sounds waves (ear), pressure waves (touch). All interactions occur via vibrational energies.
Something else to consider, how Brain wave entrainment fits into the picture. The system with the greater frequency slows, and the other accelerates. When you sense a Stimuli (light waves or sounds waves). Brain waves will automatically follow the frequency if they are in the same period. A bit like "Monkey See" - "Monkey Do"
This could explain the "Monkey Mind" syndrome people experience when they start to monitor their thoughts? Its involuntary process of harmonization or synchronization going on with the internal waves and external waves. This could explain why when you focus awareness on the no-thing, the nameless, stillness - that frequency follows to a low frequency brain wave (calm and tranquil feelings of bliss).
In Everyday life, human behaviour is often conformist in nature. We relate better when our behaviours mimic one another or fall into unison. So many expressions, "We're on the same Wave-Length, "Birds of Feather Flock together" follow this very basic principle of harmonisation or synchronization.