If youre friend ducks lover really is worth it go for ducks assiette.
Grilled foie gras terrine with chilli or chipotle.
Roasted half duck slowly rested
Confit duck legs ballotine with chinese five spice, orange and cloves. You can peel the thin layer of orange skin flat, candize it, lay it onto cling film together so it can do the job of the "skin" in the ballotine, and then make green herbs crumble with ducks jus reduced so it jellyfies and then roll the meat in that. Chill to set and you have starter and maincourse together.
If he is duck purist you could just roast whole duck, firstly stuff it with A: Oranges and thyme or B: apples garlic and marjoram and roast starting with 200, then lowering to 180. This is the most dificult part. You have to have a clue when the duck has had enough. My best guess on a bird of 1.5kg would be 30 mins max, but i never measure time, i just touch the duck. Then you rest it for amount of time you cooked it.
Then you split it in half, take ribcage bones out, all the other leaving just the leg bone in. press the breast with leg together and chill.
Perfect with mashed potato or brussel sprouts or well made cabbage. Wine? under duck, not over
Personaly i think properly roasted duck is better than any other gimmicks you would try to do, but as usual with cooking, get basics right is the most difficult shite