"The muscles are severely atrophied and the internal organs appear to be under-developed. The sensory organs, including the eyes, do not appear to function at all.
The brain, however, is well developed and draws on a high proportion of the body's blood supply. It is a mystery as to how this creature can sustain itself without external support."
The above quote is information you get from studying deceased bodies of a particularly advanced alien race in the original X-COM game, released in 1994.
(The X-COM in-universe explanation for the aliens' physiology is more psionic than cybernetic, as OP suggests. This makes OP a bit more credible than the Microprose writers, at least if your object is a discussion about plausible aliens or far-future humans in the real world within the known laws of physics. The aliens' psionic powers are kinda terrifying AF, so the Microprose prose does just fine for its intended purpose: Good storytelling for a computer game that makes no attempt to be fully real-world plausible / "hard" SF.)
The brain, however, is well developed and draws on a high proportion of the body's blood supply. It is a mystery as to how this creature can sustain itself without external support."
The above quote is information you get from studying deceased bodies of a particularly advanced alien race in the original X-COM game, released in 1994.
(The X-COM in-universe explanation for the aliens' physiology is more psionic than cybernetic, as OP suggests. This makes OP a bit more credible than the Microprose writers, at least if your object is a discussion about plausible aliens or far-future humans in the real world within the known laws of physics. The aliens' psionic powers are kinda terrifying AF, so the Microprose prose does just fine for its intended purpose: Good storytelling for a computer game that makes no attempt to be fully real-world plausible / "hard" SF.)