Gluten-free make-ahead dessert?

I saw this too late but maybe someone will benefit in the future - coconut macaroons with their little bottoms dipped in chocolate.

what about any type of ice-box cake? So many GF cookie options you can use. It is make ahead, and usually a crowd-pleasing dessert

This cake is incredible, very easy and rich chocolate-y flavor. Really needs to be served with some whipped cream and berries. Great made a day or two a head
https://www.davidlebovitz.com/shf-27-chocolat-1/

Poached pears.
In white wine and light sugar syrup.
Top with ganache and/or whipped cream.
Peches Melba (if you can get good peaches).
Block of aged parmesan, some grapes or other fruit to nibble, walnuts, port or Vin Santo to drink.
Creme bruleè.
A rich bread pudding to be served with a creme anglaise or ice cream.

Try a pavlova! It's elegant, easy, and a crowd pleaser. You can prepare the merengue, fruit, and whipped cream in advance and then assemble it at the last minute.
If you don't have enough time to make your own merengue, you could use store bought meringues to make an Eton mess instead. Not quite as pretty, but still delicious!