My experience is strictly from a beginner’s perspective. We brought home three Buff Orpington ducks last March 16th. Although the timing was in direct response to the complete lack of eggs in the store the plan to get ducks was researched for countless hours.
Although eggs were the catalyst for the initial purpose the companionship and responsibility that they brought my teenage daughter were so vital during the lockdown we jokingly call them emotional support ducks. They are completely chill under every situation except aircraft flying over or the rake being used. (Not towards them, just it’s existence).
As for their contribution: eggs, of course. They never stopped laying this winter. We housed them overnight in a small coop/ run in our shed as our low temperatures in Spokane can stay well below freezing for weeks. During the day they had full run of our backyard with an igloo of sorts made from straw bales for shelter.
They have two kiddie size pools (repurposed jet engine intake covers) available most of the year. The water from these pools is poured on garden plants when it gets too ducky. The feathers from molting are collected by small birds early in the mornings. My suburban neighbors refer to our yard as a nature sanctuary. We have even had a frog show up. The ducks did more for the community aspect than I imagined as families bring their children and grandchildren to see them.
My daughter and my self repeatedly say that no kid should have to grow up without ducks.