As Vicithebest said, Draco got a redemption arc at Cursed Child if you want it to be canon (I really don't) but I don't think he deserves any redemption at all. I don't think Draco is neither good or a bad, he put himself in a situation he didn't control because it was what everybody expected from him. I think he didn't even realise what was going everything about until it was too late. Even thou, I don't think either that the "good" things he did at the end of the saga was really because he was "good" but because of fear. We have to admmit he was kinda coward.
On the other hand, Snape really DID deserve a redemption arc. He's one of the most beautifully written characters of the series and he's so complex. I share the opinion that "everybody" hates Snape only because Harry hates him. We see the books through Harry's eyes and Harry ignores almost on purpose the "bad habits" every other professor have. Flitwick bullied Neville also, McGonagall bullied Neville and called him names! Detentions were going to the Forbidden Forest! Snape was harsh, but we don't know how he was with Ravenclaws or Hufflepuffs because Griffindor always shared potion class with Slytherin. I really think he was probably the best teacher Hogwarts had. He saved Harry so many times despite hating him. He was always in the middle of the path of the Trio because he cared about the well-being of the students and they always went against the rules.
Maybe he had not the best actitude, no one was having that at Hogwarts, but he did deserve to be a hero.
Harry was always such an asshole.