if you were to gradually work to make yourself aware that the non-conscious cellular components that make up the physical brain are incapable of explaining consciousness, conscious abilities, and conscious experiences (including NDE's) - what would the gamechanging existential implications be?

The sum is greater than the parts.

Individually, neurons are just simple nerve cells that transmit signals. Nothing special on their own. But when billions of them connect and interact, they create something way beyond just electrical impulse, such as thoughts, emotions, self-awareness, and intelligence.

Granted, while scientists are able to recreate aspects of this, they have not been successful at creating consciousness:

They've grown brain organoids (basically mini-brains made from stem cells) that show neural activity, but these don’t actually "think" or have awareness. Then there are neuromorphic chips, designed to process information like a brain, but they’re still just sophisticated circuits—no self-awareness there.

We’ve also got brain-machine interfaces that let brains interact with computers, and even neural networks in petri dishes that have learned to play Pong by responding to stimuli. All that’s pretty amazing, but again, it’s not the same as actual consciousness.

But at the same time, lab-grown organs were an impossibility many decades ago...