This reminds me of something Rupert Sheldrake says is possible - that consciousness is 'off-site', that the body is more of a radio receptor.
Consciousness is an emergent phenomenon entirely dependent on and contained within the brain.
brain-as-a-radio-antenna is a common trope amongst those who would believe that meatspace isn't capable of generating consciousness alone (always looking for some sort of elan vital, to equate with another pursuit for the magic stuff of life).
From a purposely scientific perspective, we have to begin with the working assumption that materialism is true, until such point that it is conclusively proven false.
There is no evidence that the brain works in any way like an antenna, at least insofar as any electromagnetic waves or other such messaging systems supported by the physics of our current world as we know it.
Thus, the brain-as-antenna thinking necessarily pre-supposes an other-worldly explanation; it assumes what it's trying to prove.
Even if it were true (HIGHLY unlikely), we can't begin with that as the starting point in our search for understanding it. Otherwise, our brains are incredibly adept at shaping our thoughts and concepts to fit those prescribed notions of animacy and otherworldliness.
It's no wonder that many pseudoscientific principles BEGIN with the presupposition that you have to be willing to believe in order for the effect to become apparent.
If you shut off all outside signals, the brain works just fine, there's no effect at all. (Except maybe the stress of whatever situation you're in that landed you in a super shielded bunker. )
Materialism, aka "physicalism", simply posits that all phenomena have an underlying physical basis, i.e., no "spooky" or magic stuff.
https://plato.stanford.edu/entries/physicalism/
Quantum mechanics follows from physicalism by demonstrating that the physical nature of reality is incredibly complex and counterintuitive, particularly at quantum scales.
But that in no way implies that quantum mechanics leads to non-materialism or opens the door for materialism to be false. It simply becomes subsumed into materialism itself:
materialism requires that all phenomena be ultimately explainable via physical explanations, and those explanations must account for quantum-mechanical phenomena.
Materialism does the same thing though, as you observed:
> we have to begin with the working assumption that materialism is true
To be clear, I'm a materialist, but that's precisely why I dislike poor arguments.
How would one falsify this?
Consciousness exists. It ceases to exist when the brain is damaged or killed. We can predictably modify conscious systems with drugs and experiences. Particular types of injury and illness sometimes result in predictable consequences, letting us know things such as that the hippocampus is critical to memory, and that whatever hierarchy of semantic meaning is stored in the brain, neurons in the hippocampus represent ontological peaks in the mental landscape of constructed meaning.
With a sufficiently high resolution brain interface, you could record, replay, simulate, and share experiences between consciousnesses. If the mind is an emergent phenomena brought about within the confines of the skull, shared experience will be possible, up to the point that your subjective experience of being another person will be complete for the duration of the replay. If there's some outside factor playing a role in consciousness, it will be missing and likely prevent attempts at recording experience.
Using the radio metaphor, I think I could edit the radio so that the signal would be heard differently. Just turning up the volume is a sort of alteration of consciousness, as would be increasing/decreasing the bass/treble.
These are alterations to the way the sound is experienced, but do not affect the signal itself.
Maybe taking drugs would be akin to running the received signal through some sort of special effects board? Ie a different/unusual type of alteration to the signal.