I am keeping my expectations down but it's not impossible to get IIs during the holidays. My friend got an II from Cornell at 11 pm on Christmas Eve last year so I think anything goes.
Some deans are actually getting a break from other responsibilities so that they can send invites even on holidays. I would not expect schools to be doing interviews between 12/23 and 1/3 but they might send invites for 2021 interview slots over the holidays. Keep refreshing and check that junk mail file, too. 😉