It’s unclear to me that this case would be covered though? It’s not hard if you lose your legs or arms. Pain and related topics are likely excluded from your standard policy.
Of course, it's likely harder to prove such a claim, as the insurance companies look out for fraud. But if you have a clear and well-documented history, medical files, etc., I would think you should be eligible.
Note that your megacorp group insurance policy is likely more limited, e.g. it may not have any coverage for partial disability.
Happy to be corrected by those more knowledgeable.
Carpal tunnel is a medical condition. You can take an xray and see inflamation and rule it.
You can't really do that with pain or brainfog. There is no test "how real is this persons pain".