That is a huge question! For whom are you shopping? Kids, adults, nerds, other? Are they humble or snobs? Are they picky? Are there actual special considerations? Are there any items in your grocery stores that can be used in/for Christmas gifts? If you are free in these shops to buy whatever you want within reason, you might buy something during a grocery store shop that will contribute toward your Christmas activities. You might put together the ingredients for a recipe and package it in a bowl or on a platter. You might purchase the ingredients for someone's fave dish and prepare it for them. Some stores have appealing little stocking stuffers. You could buy wrapping supplies during one of these shops, but these items might cost less elsewhere. There are clothing and shoe store shops where you can buy clothing or shoes. The reimbursements might be more of a discount, but you could buy clothes or shoes and give them as gifts. You could also do more shops of any type to accumulate cash that you can give directly or spend anywhere.
My garden in England is full of eating-out places, for heat waves, warm September evenings, or lunch on a chilly Christmas morning. (Mary Quant)