Becoming a big sibling
Somebody at your house is about to be someone new. They were the kid, and now they are becoming the older kid, and the transition is not entirely comfortable for them.
Everyone in the extended family has been buying things for the baby for months. The baby has more clothes than fit in a drawer. The baby is not, at this stage, aware.
The older kid is aware.
What actually helps
You cannot make the transition invisible. They are going to have complicated feelings about it, and that is developmentally correct, and there is no gift that dissolves those feelings. What a gift can do is a smaller thing, which is to mark them as still the specific person they were, in the middle of a change that is being described in terms of the baby.
You do this with attention that's about them and not about the sibling role. A gift that has their name and their current interests inside it, and no reference to the baby whatsoever, is a good example.
What this is
Madejustfor.me makes a personalized playable card for one specific kid. You spend three minutes on the order form describing them: their name, their age, what they are specifically into right now, the mood you'd want the little game to have.
You pay nine dollars. A minute or two later, a link comes back. It's a small game, on their favorite thing, in their name.
You hand it to them the day the baby comes home. Or the day before. Or the day they're staying with grandparents while the birth happens. Whenever the transition is landing for them, you have a small piece of evidence that says: you are still the specific person you were, and I still see you.