Prime Sinner >>>> Prime Berdych by light years. If anything, Berdych is the knock-off of Sinner (and not even a good one at that).
To make a Dragon Ball style comparison, if Berdych was kid Goku, then Sinner would be Ultra Instinct Goku.
Also, when Sinner played against Nadal in those three matches you mentioned, it is undeniable that Sinner was significantly further away from his prime than Nadal was. Besides, what about prime 2008-2013 Nadal's game could possibly do meaningful damage to prime 2024-present version of Sinner?? Sinner is taller, he is more durable, he hits the ball much harder and with greater precision, he has better FH than Nadal, better BH too, better serve, better volleys, better passing shots, and is mentally stronger.
The only real advantage peak Nadal would have over peak Sinner is his running speed, but that alone would not compensate for the numerous areas in which Sinner is better than Nadal.