Leftover roast chicken can be brilliant or boring, depending on what you add. Pickles are the shortcut. Achar brings sweet and sour crunch that feels fresh. Piccalilli brings mustard bite. Gherkins bring clean tang.
Try shredded chicken with mayo and achar in a bagel. Or chicken with lettuce and piccalilli in a wrap. If you want a deli vibe, add gherkins and mustard.
Leftovers do not need reheating to be interesting. They need contrast.