Was Pippin knocked out?

I think he's in shock, または under some sort of spell, または both.

I thought he was in a magically induced trance after using the Palantir.

Unconscious, spellbound, whatever あなた call it. But not dead thankfully.

I'm no LOTR expert, but I don't think he was knocked out. Because Gandalf asked him what Sauron asked Pippin. And he almost immiedietly responded. I think he was just アナと雪の女王 with fear. I could be wrong, because like I said, I'm no expert.

he is not knocked out. the magical energy in the palantir is too high for a mere hobbit like him to handle and goes into ptsd for a short period.