We did ours last Friday. Lots has gone in the freezer, the rest is long dated to at least Boxing Day. For example, potato salad, vegetarian pakoras and coleslaw are all in there whether or not they say they are suitable for freezing. (You can Google how/if to freeze things and how long for, if unsure.) Meat, quiches, stuffing, pork pies, vegetables, frozen fruit for on top of the merigues which amazingly doesn't go to mush when defrosted (how?) - I know this cos I've had it before.
We do a lot with store cupboard ingredients too.
In fairness it was for a very small number of people but if I had a chest freezer I could have done it for more. We honed the ability to do shopping well ahead and plan meals round that during lockdown, although I was brought up that way to an extent. You do have to be not too fussy to shop ahead though ie if it won't work, you don't have it.
Other than that I used to go very late (eg 2 am) to a very large Tesco that was open 24/7, really enjoyed it near Christmas with likeminded people, the radio on, the staff were usually in a good mood especially if you were friendly to them. Not sure if any supermarkets are still 24/7 as they narrowed their opening hours due to Covid. If a morning person, go when they open, a few days beforehand IMO. Not Xmas Eve at all though!