can Superman deflect a lightsaber

Aha, I think no problem

If there's a kryptonite stash inside it, then yes. Great question though. I'm gonna insist that it'd just burn his clothes up at most. I don't want to think it depends on the version, coz even the dceu superman at his peak is impermeable to energy attacks. Though for any version of him that's been significantly weakened, yes, it would.
Though that gets me wondering if wonder woman would be cut. We know her weakness is bladed instruments, and she's resistant to energy attacks, and while a light saber mimics an actual blade, it is just a concentrated beam of light with no actual cutting edge. What do y'all think

Depends on the color. Green lightsabers cut though him easily. Red not so much but make him really moody! Others... Wait! Lightsabers are made with kryptonite right? No? Kyber crystals? Oh, never mind then! 😆