I feel for you. I have had a really really really hard time watching anything in the MCU really ever since Endgame. And I've only seen Endgame once. I just can't bring myself to sit through it again. Even the parts that aren't heartbreaking.
But yes. I think Steve would definitely know Happy, just because Happy was usually in Tony's orbit in some capacity. I don't think Happy would have known about Tony and Steve burying the hatchet, but he's very 🍿about the whole thing, though obviously Team Iron Man.