To be fair, he did win 5 matches to reach the SF for the 1st time ever in his career. So, there’s something there.
While you are correct that the pressure of winning CYGS is greater than what he will feel tomorrow; there is still A LOT of pressure due the circumstances he put himself too.
I have said it before: He knows that tomorrow is his last slam match of 2022. If he doesn’t win tomorrow, he will come into 2023 either he will be behind two slams or three slams against Nadal. While 2 slams deficit is not big, he definitely feels like it is a huge gap due to his age and other circumstances.
He wants to end 2022 Slam season at least 1 slam behind Nadal going into 2023 season.
I agree with you that the pressure on Novak is not unlike the pressure of last year's USO, due to what he is up against, in the sense that he may not play another Major until Roland Garros next year. And he's getting long in the tooth, and opportunities will lessen. Also given that Rafa could yet win the USO again. If healthy, he'll be a top favorite. Wimbledon keeps Novak in touching distance. Without it, who knows, but he may be 36 before he plays another Major. He already needs 3 to pass Nadal.
As to Kyrgios, he has done what he set out to do, so far, which was basically hold it together well enough to get this far. I do not believe he doesn't care. But I do believe he cares less than Novak. He's always been able to get up for big matches, and he likes the show against top players. Someone on a thread made the point that it was #40 against #1, or something. Technically, it's #3 against #40, but even still...Nick has never been a threat due to ranking. Of what was on offer, this Wimbledon, and with Rafa out, who's a better option for threat?
There is a chance that Nick completely collapses under the pressure. There is a chance that Novak comes in large and in-charge, and Nick has nothing to say about it. But it is best of 5, so most likely it will be a competitive match. How competitive, how long, how crazy it might get...that's what we're all tuning in to see.