The smurfs endorsed a breakfast cereal in the USA during their tv run. Do you remember what cereal they endorsed?
There was a cereal called “Smurf-Berry Crunch”. I think it came on the market in 1983. It contained blue and red puffs of oats, corn and wheat, that had the shape of berries. And our friend Vic informed us that there was also a Smurf Magic Stars with marshmallow stars in it, that came out in the late 1980s by Post Cereal. Thanks a smurf Vic!