The only legitimate confirmation would be a doctor's diagnosis.
So you're saying that his speeches, energy, demeanor, etc... for the 2020-2024 era were just as good as in the videos I posted?
Hardly...
And setting up this "unless you have a doctors diagnosis" standard is disingenuous for two reasons.
A) "The only way you can prove me wrong is if you get a piece of data that's HIPAA protected and won't be publicly available", that's setting up a standard that can never be met. It'd be like someone demanding "you can't claim Trump has a Narcissistic personality issue unless you show me the signed form from his personal psychologist officially diagnosing him with that" -- yeah, that's a piece of information that simply can't be provided.
B) No, you don't always need a doctor's diagnosis for confirmation on certain things. That's just a deflection and stall tactic in these types of debates.
Much like you don't need to have an MD license (or wait for an MD to "officially make a statement") to know that a person is having a heart attack.
No to mention, with the level of denial some people exhibited pertaining to refusing to acknowledge the decline of a president they like, having a doctor say it wouldn't be sufficient for them anyway, they'd just move the goalposts and bring up the fact that in American medicine, the misdiagnosis rate ranges from 5-15% -- thereby having another brick to throw up on the wall for why "that doesn't count"
You don't need an MD to use your eyes and ears and see a man who gave powerful speeches, commanded rooms, and had solid public debate performances, and then 10 years later, constantly stammered over his words, clearly couldn't collect his thoughts -- and on some occasions, wandered around like a Roomba trying to find its charging station, and realize that there was significant decline happening.